path: root/src/mscorlib/src/System/Convert.cs

// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

/*============================================================
**
**
**
** Purpose: Home for static conversion methods.
**
**
===========================================================*/

using System;
using System.Globalization;
using System.Threading;
using System.Reflection;
using System.Runtime.CompilerServices;
using System.Runtime.InteropServices;
using System.Runtime.Versioning;
using System.Security;
using System.Diagnostics.Contracts;


namespace System {    

    [Flags]
    public enum Base64FormattingOptions {
        None = 0,
        InsertLineBreaks = 1
    }

    // Returns the type code of this object. An implementation of this method
    // must not return TypeCode.Empty (which represents a null reference) or
    // TypeCode.Object (which represents an object that doesn't implement the
    // IConvertible interface). An implementation of this method should return
    // TypeCode.DBNull if the value of this object is a database null. For
    // example, a nullable integer type should return TypeCode.DBNull if the
    // value of the object is the database null. Otherwise, an implementation
    // of this method should return the TypeCode that best describes the
    // internal representation of the object.
    // The Value class provides conversion and querying methods for values. The
    // Value class contains static members only, and it is not possible to create
    // instances of the class.
    //
    // The statically typed conversion methods provided by the Value class are all
    // of the form:
    //
    //    public static XXX ToXXX(YYY value)
    //
    // where XXX is the target type and YYY is the source type. The matrix below
    // shows the set of supported conversions. The set of conversions is symmetric
    // such that for every ToXXX(YYY) there is also a ToYYY(XXX).
    //
    // From:  To: Bol Chr SBy Byt I16 U16 I32 U32 I64 U64 Sgl Dbl Dec Dat Str
    // ----------------------------------------------------------------------
    // Boolean     x       x   x   x   x   x   x   x   x   x   x   x       x
    // Char            x   x   x   x   x   x   x   x   x                   x
    // SByte       x   x   x   x   x   x   x   x   x   x   x   x   x       x
    // Byte        x   x   x   x   x   x   x   x   x   x   x   x   x       x
    // Int16       x   x   x   x   x   x   x   x   x   x   x   x   x       x
    // UInt16      x   x   x   x   x   x   x   x   x   x   x   x   x       x
    // Int32       x   x   x   x   x   x   x   x   x   x   x   x   x       x
    // UInt32      x   x   x   x   x   x   x   x   x   x   x   x   x       x
    // Int64       x   x   x   x   x   x   x   x   x   x   x   x   x       x
    // UInt64      x   x   x   x   x   x   x   x   x   x   x   x   x       x
    // Single      x       x   x   x   x   x   x   x   x   x   x   x       x
    // Double      x       x   x   x   x   x   x   x   x   x   x   x       x
    // Decimal     x       x   x   x   x   x   x   x   x   x   x   x       x
    // DateTime                                                        x   x
    // String      x   x   x   x   x   x   x   x   x   x   x   x   x   x   x
    // ----------------------------------------------------------------------
    //
    // For dynamic conversions, the Value class provides a set of methods of the
    // form:
    //
    //    public static XXX ToXXX(object value)
    //
    // where XXX is the target type (Boolean, Char, SByte, Byte, Int16, UInt16,
    // Int32, UInt32, Int64, UInt64, Single, Double, Decimal, DateTime,
    // or String). The implementations of these methods all take the form:
    //
    //    public static XXX toXXX(object value) {
    //        return value == null? XXX.Default: ((IConvertible)value).ToXXX();
    //    }
    //
    // The code first checks if the given value is a null reference (which is the
    // same as Value.Empty), in which case it returns the default value for type
    // XXX. Otherwise, a cast to IConvertible is performed, and the appropriate ToXXX()
    // method is invoked on the object. An InvalidCastException is thrown if the
    // cast to IConvertible fails, and that exception is simply allowed to propagate out
    // of the conversion method.
        
    // Constant representing the database null value. This value is used in
    // database applications to indicate the absense of a known value. Note
    // that Value.DBNull is NOT the same as a null object reference, which is
    // represented by Value.Empty.
    //
    // The Equals() method of DBNull always returns false, even when the
    // argument is itself DBNull.
    //
    // When passed Value.DBNull, the Value.GetTypeCode() method returns
    // TypeCode.DBNull.
    //
    // When passed Value.DBNull, the Value.ToXXX() methods all throw an
    // InvalidCastException.

    public static class Convert {
        
        //A typeof operation is fairly expensive (does a system call), so we'll cache these here
        //statically.  These are exactly lined up with the TypeCode, eg. ConvertType[TypeCode.Int16]
        //will give you the type of an Int16.
        internal static readonly RuntimeType[] ConvertTypes = {
            (RuntimeType)typeof(System.Empty),
            (RuntimeType)typeof(Object),
            (RuntimeType)typeof(System.DBNull),
            (RuntimeType)typeof(Boolean),
            (RuntimeType)typeof(Char),
            (RuntimeType)typeof(SByte),
            (RuntimeType)typeof(Byte),
            (RuntimeType)typeof(Int16),
            (RuntimeType)typeof(UInt16),
            (RuntimeType)typeof(Int32),
            (RuntimeType)typeof(UInt32),
            (RuntimeType)typeof(Int64),
            (RuntimeType)typeof(UInt64),
            (RuntimeType)typeof(Single),
            (RuntimeType)typeof(Double),
            (RuntimeType)typeof(Decimal),
            (RuntimeType)typeof(DateTime),
            (RuntimeType)typeof(Object), //TypeCode is discontinuous so we need a placeholder.
            (RuntimeType)typeof(String)
        };

        // Need to special case Enum because typecode will be underlying type, e.g. Int32
        private static readonly RuntimeType EnumType = (RuntimeType)typeof(Enum);

        internal static readonly char[] base64Table = {'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O',
                                                       'P','Q','R','S','T','U','V','W','X','Y','Z','a','b','c','d',
                                                       'e','f','g','h','i','j','k','l','m','n','o','p','q','r','s',
                                                       't','u','v','w','x','y','z','0','1','2','3','4','5','6','7',
                                                       '8','9','+','/','=' };        

        private const Int32 base64LineBreakPosition = 76;       

#if _DEBUG
        private static bool TriggerAsserts = DoAsserts();
        private static bool DoAsserts() {
            Contract.Assert(ConvertTypes!=null, "[Convert.cctor]ConvertTypes!=null");
            Contract.Assert(ConvertTypes.Length == ((int)TypeCode.String + 1), "[Convert.cctor]ConvertTypes.Length == ((int)TypeCode.String + 1)");
            Contract.Assert(ConvertTypes[(int)TypeCode.Empty]==typeof(System.Empty),
                            "[Convert.cctor]ConvertTypes[(int)TypeCode.Empty]==typeof(System.Empty)");
            Contract.Assert(ConvertTypes[(int)TypeCode.String]==typeof(String),
                            "[Convert.cctor]ConvertTypes[(int)TypeCode.String]==typeof(System.String)");
            Contract.Assert(ConvertTypes[(int)TypeCode.Int32]==typeof(int),
                            "[Convert.cctor]ConvertTypes[(int)TypeCode.Int32]==typeof(int)");
            return true;
        }
#endif

        public static readonly Object DBNull = System.DBNull.Value;

        // Returns the type code for the given object. If the argument is null,
        // the result is TypeCode.Empty. If the argument is not a value (i.e. if
        // the object does not implement IConvertible), the result is TypeCode.Object.
        // Otherwise, the result is the type code of the object, as determined by
        // the object's implementation of IConvertible.
        [Pure]
        public static TypeCode GetTypeCode(object value) {
            if (value == null) return TypeCode.Empty;
            IConvertible temp = value as IConvertible;
            if (temp != null)
            {
                return temp.GetTypeCode();
            }
            return TypeCode.Object;
        }

        // Returns true if the given object is a database null. This operation
        // corresponds to "value.GetTypeCode() == TypeCode.DBNull".
        [Pure]
        public static bool IsDBNull(object value) {
            if (value == System.DBNull.Value) return true;
            IConvertible convertible = value as IConvertible;
            return convertible != null? convertible.GetTypeCode() == TypeCode.DBNull: false;
        }

        // Converts the given object to the given type. In general, this method is
        // equivalent to calling the Value.ToXXX(value) method for the given
        // typeCode and boxing the result.
        //
        // The method first checks if the given object implements IConvertible. If not,
        // the only permitted conversion is from a null to TypeCode.Empty, the
        // result of which is null.
        //
        // If the object does implement IConvertible, a check is made to see if the
        // object already has the given type code, in which case the object is
        // simply returned. Otherwise, the appropriate ToXXX() is invoked on the
        // object's implementation of IConvertible.
        public static Object ChangeType(Object value, TypeCode typeCode) {
            return ChangeType(value, typeCode, Thread.CurrentThread.CurrentCulture);
        }

        public static Object ChangeType(Object value, TypeCode typeCode, IFormatProvider provider) {
            if (value == null && (typeCode == TypeCode.Empty || typeCode == TypeCode.String || typeCode == TypeCode.Object)) {
                return null;
            }
        
            IConvertible v = value as IConvertible;
            if (v == null) {
                throw new InvalidCastException(Environment.GetResourceString("InvalidCast_IConvertible"));
            }

            // This line is invalid for things like Enums that return a TypeCode
            // of Int32, but the object can't actually be cast to an Int32.
            //            if (v.GetTypeCode() == typeCode) return value;
            switch (typeCode) {
            case TypeCode.Boolean:
                return v.ToBoolean(provider);
            case TypeCode.Char:
                return v.ToChar(provider);
            case TypeCode.SByte:
                return v.ToSByte(provider);
            case TypeCode.Byte:
                return v.ToByte(provider);
            case TypeCode.Int16:
                return v.ToInt16(provider);
            case TypeCode.UInt16:
                return v.ToUInt16(provider);
            case TypeCode.Int32:
                return v.ToInt32(provider);
            case TypeCode.UInt32:
                return v.ToUInt32(provider);
            case TypeCode.Int64:
                return v.ToInt64(provider);
            case TypeCode.UInt64:
                return v.ToUInt64(provider);
            case TypeCode.Single:
                return v.ToSingle(provider);
            case TypeCode.Double:
                return v.ToDouble(provider);
            case TypeCode.Decimal:
                return v.ToDecimal(provider);
            case TypeCode.DateTime:
                return v.ToDateTime(provider);
            case TypeCode.String:
                return v.ToString(provider);
            case TypeCode.Object:
                return value;
            case TypeCode.DBNull:
                throw new InvalidCastException(Environment.GetResourceString("InvalidCast_DBNull"));
            case TypeCode.Empty:
                throw new InvalidCastException(Environment.GetResourceString("InvalidCast_Empty"));
            default:
                throw new ArgumentException(Environment.GetResourceString("Arg_UnknownTypeCode"));
            }
        }

        internal static Object DefaultToType(IConvertible value, Type targetType, IFormatProvider provider) {
            Contract.Requires(value != null, "[Convert.DefaultToType]value!=null");
            if (targetType==null) {
                throw new ArgumentNullException("targetType");
            }
            Contract.EndContractBlock();

            RuntimeType rtTargetType = targetType as RuntimeType;

            if (rtTargetType != null)
            {
                if (value.GetType() == targetType)
                {
                    return value;
                }

                if (rtTargetType == ConvertTypes[(int)TypeCode.Boolean])
                    return value.ToBoolean(provider);
                if (rtTargetType == ConvertTypes[(int)TypeCode.Char])
                    return value.ToChar(provider);
                if (rtTargetType == ConvertTypes[(int)TypeCode.SByte])
                    return value.ToSByte(provider);
                if (rtTargetType == ConvertTypes[(int)TypeCode.Byte])
                    return value.ToByte(provider);
                if (rtTargetType == ConvertTypes[(int)TypeCode.Int16])
                    return value.ToInt16(provider);
                if (rtTargetType == ConvertTypes[(int)TypeCode.UInt16])
                    return value.ToUInt16(provider);
                if (rtTargetType == ConvertTypes[(int)TypeCode.Int32])
                    return value.ToInt32(provider);
                if (rtTargetType == ConvertTypes[(int)TypeCode.UInt32])
                    return value.ToUInt32(provider);
                if (rtTargetType == ConvertTypes[(int)TypeCode.Int64])
                    return value.ToInt64(provider);
                if (rtTargetType == ConvertTypes[(int)TypeCode.UInt64])
                    return value.ToUInt64(provider);
                if (rtTargetType == ConvertTypes[(int)TypeCode.Single])
                    return value.ToSingle(provider);
                if (rtTargetType == ConvertTypes[(int)TypeCode.Double])
                    return value.ToDouble(provider);
                if (rtTargetType == ConvertTypes[(int)TypeCode.Decimal])
                    return value.ToDecimal(provider);
                if (rtTargetType == ConvertTypes[(int)TypeCode.DateTime])
                    return value.ToDateTime(provider);
                if (rtTargetType == ConvertTypes[(int)TypeCode.String])
                    return value.ToString(provider);
                if (rtTargetType == ConvertTypes[(int)TypeCode.Object])
                    return (Object)value;
                //  Need to special case Enum because typecode will be underlying type, e.g. Int32
                if (rtTargetType == EnumType)
                    return (Enum)value;
                if (rtTargetType == ConvertTypes[(int)TypeCode.DBNull])
                    throw new InvalidCastException(Environment.GetResourceString("InvalidCast_DBNull"));
                if (rtTargetType == ConvertTypes[(int)TypeCode.Empty])
                    throw new InvalidCastException(Environment.GetResourceString("InvalidCast_Empty"));
            }

            throw new InvalidCastException(Environment.GetResourceString("InvalidCast_FromTo", value.GetType().FullName, targetType.FullName));
        }

        public static Object ChangeType(Object value, Type conversionType) {
            return ChangeType(value, conversionType, Thread.CurrentThread.CurrentCulture);
        }

        public static Object ChangeType(Object value, Type conversionType, IFormatProvider provider) {
            if( conversionType == null) {
                throw new ArgumentNullException("conversionType");
            }
            Contract.EndContractBlock();

            if( value == null ) {
                if(conversionType.IsValueType) {
                    throw new InvalidCastException(Environment.GetResourceString("InvalidCast_CannotCastNullToValueType"));
                }
                return null; 
            }

            IConvertible ic = value as IConvertible;
            if (ic == null) {
                if ( value.GetType() == conversionType) {
                    return value;
                }
                throw new InvalidCastException(Environment.GetResourceString("InvalidCast_IConvertible"));
            }

            RuntimeType rtConversionType = conversionType as RuntimeType;

            if (rtConversionType==ConvertTypes[(int)TypeCode.Boolean])
                return ic.ToBoolean(provider);
            if (rtConversionType==ConvertTypes[(int)TypeCode.Char])
                return ic.ToChar(provider);
            if (rtConversionType==ConvertTypes[(int)TypeCode.SByte])
                return ic.ToSByte(provider);
            if (rtConversionType==ConvertTypes[(int)TypeCode.Byte])
                return ic.ToByte(provider);
            if (rtConversionType==ConvertTypes[(int)TypeCode.Int16]) 
                return ic.ToInt16(provider);
            if (rtConversionType==ConvertTypes[(int)TypeCode.UInt16])
                return ic.ToUInt16(provider);
            if (rtConversionType==ConvertTypes[(int)TypeCode.Int32])
                return ic.ToInt32(provider);
            if (rtConversionType==ConvertTypes[(int)TypeCode.UInt32])
                return ic.ToUInt32(provider);
            if (rtConversionType==ConvertTypes[(int)TypeCode.Int64])
                return ic.ToInt64(provider);
            if (rtConversionType==ConvertTypes[(int)TypeCode.UInt64])
                return ic.ToUInt64(provider);
            if (rtConversionType==ConvertTypes[(int)TypeCode.Single])
                return ic.ToSingle(provider);
            if (rtConversionType==ConvertTypes[(int)TypeCode.Double])
                return ic.ToDouble(provider);
            if (rtConversionType==ConvertTypes[(int)TypeCode.Decimal])
                return ic.ToDecimal(provider);
            if (rtConversionType==ConvertTypes[(int)TypeCode.DateTime])
                return ic.ToDateTime(provider);
            if (rtConversionType==ConvertTypes[(int)TypeCode.String])
                return ic.ToString(provider);
            if (rtConversionType==ConvertTypes[(int)TypeCode.Object])
                return (Object)value;

            return ic.ToType(conversionType, provider);
        }

        [MethodImpl(MethodImplOptions.NoInlining)]
        private static void ThrowCharOverflowException() { throw new OverflowException(Environment.GetResourceString("Overflow_Char")); }

        [MethodImpl(MethodImplOptions.NoInlining)]
        private static void ThrowByteOverflowException() { throw new OverflowException(Environment.GetResourceString("Overflow_Byte")); }

        [MethodImpl(MethodImplOptions.NoInlining)]
        private static void ThrowSByteOverflowException() { throw new OverflowException(Environment.GetResourceString("Overflow_SByte")); }

        [MethodImpl(MethodImplOptions.NoInlining)]
        private static void ThrowInt16OverflowException() { throw new OverflowException(Environment.GetResourceString("Overflow_Int16")); }

        [MethodImpl(MethodImplOptions.NoInlining)]
        private static void ThrowUInt16OverflowException() { throw new OverflowException(Environment.GetResourceString("Overflow_UInt16")); }

        [MethodImpl(MethodImplOptions.NoInlining)]
        private static void ThrowInt32OverflowException() { throw new OverflowException(Environment.GetResourceString("Overflow_Int32")); }

        [MethodImpl(MethodImplOptions.NoInlining)]
        private static void ThrowUInt32OverflowException() { throw new OverflowException(Environment.GetResourceString("Overflow_UInt32")); }

        [MethodImpl(MethodImplOptions.NoInlining)]
        private static void ThrowInt64OverflowException() { throw new OverflowException(Environment.GetResourceString("Overflow_Int64")); }

        [MethodImpl(MethodImplOptions.NoInlining)]
        private static void ThrowUInt64OverflowException() { throw new OverflowException(Environment.GetResourceString("Overflow_UInt64")); }

        // Conversions to Boolean
        public static bool ToBoolean(Object value) {
            return value == null? false: ((IConvertible)value).ToBoolean(null);
        }

        public static bool ToBoolean(Object value, IFormatProvider provider) {
            return value == null? false: ((IConvertible)value).ToBoolean(provider);
        }


        public static bool ToBoolean(bool value) {
            return value;
        }

        [CLSCompliant(false)]
        public static bool ToBoolean(sbyte value) {
            return value != 0;
        }

        // To be consistent with IConvertible in the base data types else we get different semantics
        // with widening operations. Without this operator this widen succeeds,with this API the widening throws.
        public static bool ToBoolean(char value) {
            return ((IConvertible)value).ToBoolean(null);
        }

        public static bool ToBoolean(byte value) {
            return value != 0;
        }


        public static bool ToBoolean(short value) {
            return value != 0;
        }

        [CLSCompliant(false)]   
        public static bool ToBoolean(ushort value) {
            return value != 0;
        }

        public static bool ToBoolean(int value) {
            return value != 0;
        }

        [CLSCompliant(false)]   
        public static bool ToBoolean(uint value) {
            return value != 0;
        }

        public static bool ToBoolean(long value) {
            return value != 0;
        }

        [CLSCompliant(false)]   
        public static bool ToBoolean(ulong value) {
            return value != 0;
        }

        public static bool ToBoolean(String value) {
            if (value == null)
                return false;
            return Boolean.Parse(value);
        }

        public static bool ToBoolean(String value, IFormatProvider provider) {
            if (value == null)
                return false;
            return Boolean.Parse(value);
        }

        public static bool ToBoolean(float value)
        {
            return value != 0;
        }
        
        public static bool ToBoolean(double value)
        {
            return value != 0;
        }

        public static bool ToBoolean(decimal value)
        {
            return value != 0;
        }

        public static bool ToBoolean(DateTime value)
        {
            return ((IConvertible)value).ToBoolean(null);
        }
 
        // Disallowed conversions to Boolean
        // public static bool ToBoolean(TimeSpan value)

        // Conversions to Char


        public static char ToChar(object value) {
            return value == null? (char)0: ((IConvertible)value).ToChar(null);
        }

        public static char ToChar(object value, IFormatProvider provider) {
            return value == null? (char)0: ((IConvertible)value).ToChar(provider);
        }

        public static char ToChar(bool value) {
            return ((IConvertible)value).ToChar(null);
        }

        public static char ToChar(char value) {
            return value;
        }

        [CLSCompliant(false)]
        public static char ToChar(sbyte value) {
            if (value < 0) ThrowCharOverflowException();
            Contract.EndContractBlock();
            return (char)value;
        }

        public static char ToChar(byte value) {
            return (char)value;
        }

        public static char ToChar(short value) {
            if (value < 0) ThrowCharOverflowException();
            Contract.EndContractBlock();
            return (char)value;
        }

        [CLSCompliant(false)]   
        public static char ToChar(ushort value) {
            return (char)value;
        }

        public static char ToChar(int value) {
            if (value < 0 || value > Char.MaxValue) ThrowCharOverflowException();
            Contract.EndContractBlock();
            return (char)value;
        }

        [CLSCompliant(false)]   
        public static char ToChar(uint value) {
            if (value > Char.MaxValue) ThrowCharOverflowException();
            Contract.EndContractBlock();
            return (char)value;
        }

        public static char ToChar(long value) {
            if (value < 0 || value > Char.MaxValue) ThrowCharOverflowException();
            Contract.EndContractBlock();
            return (char)value;
        }

        [CLSCompliant(false)]   
        public static char ToChar(ulong value) {
            if (value > Char.MaxValue) ThrowCharOverflowException();
            Contract.EndContractBlock();
            return (char)value;
        }

        //
        // @VariantSwitch
        // Remove FormatExceptions;
        //
        public static char ToChar(String value) {
            return ToChar(value, null);
        }

        public static char ToChar(String value, IFormatProvider provider) {
            if (value == null) 
                throw new ArgumentNullException("value");
            Contract.EndContractBlock();
         
            if (value.Length != 1) 
                throw new FormatException(Environment.GetResourceString(ResId.Format_NeedSingleChar));

            return value[0];
        }

        // To be consistent with IConvertible in the base data types else we get different semantics
        // with widening operations. Without this operator this widen succeeds,with this API the widening throws.
        public static char ToChar(float value)
        {
            return ((IConvertible)value).ToChar(null);
        }

        // To be consistent with IConvertible in the base data types else we get different semantics
        // with widening operations. Without this operator this widen succeeds,with this API the widening throws.
        public static char ToChar(double value)
        {
            return ((IConvertible)value).ToChar(null);
        }

        // To be consistent with IConvertible in the base data types else we get different semantics
        // with widening operations. Without this operator this widen succeeds,with this API the widening throws.
        public static char ToChar(decimal value)
        {
            return ((IConvertible)value).ToChar(null);
        }

        public static char ToChar(DateTime value)
        {
            return ((IConvertible)value).ToChar(null);
        }


        // Disallowed conversions to Char
        // public static char ToChar(TimeSpan value)
        
        // Conversions to SByte

        [CLSCompliant(false)]
        public static sbyte ToSByte(object value) {
            return value == null? (sbyte)0: ((IConvertible)value).ToSByte(null);
        }

        [CLSCompliant(false)]
        public static sbyte ToSByte(object value, IFormatProvider provider) {
            return value == null? (sbyte)0: ((IConvertible)value).ToSByte(provider);
        }

        [CLSCompliant(false)]
        public static sbyte ToSByte(bool value) {
            return value? (sbyte)Boolean.True: (sbyte)Boolean.False;
        }

        [CLSCompliant(false)]
        public static sbyte ToSByte(sbyte value) {
            return value;
        }

        [CLSCompliant(false)]
        public static sbyte ToSByte(char value) {
            if (value > SByte.MaxValue) ThrowSByteOverflowException();
            Contract.EndContractBlock();
            return (sbyte)value;
        }

        [CLSCompliant(false)]
        public static sbyte ToSByte(byte value) {
            if (value > SByte.MaxValue) ThrowSByteOverflowException();
            Contract.EndContractBlock();
            return (sbyte)value;
        }

        [CLSCompliant(false)]
        public static sbyte ToSByte(short value) {
            if (value < SByte.MinValue || value > SByte.MaxValue) ThrowSByteOverflowException();
            Contract.EndContractBlock();
            return (sbyte)value;
        }

        [CLSCompliant(false)]   
        public static sbyte ToSByte(ushort value) {
            if (value > SByte.MaxValue) ThrowSByteOverflowException();
            Contract.EndContractBlock();
            return (sbyte)value;
        }

        [CLSCompliant(false)]
        public static sbyte ToSByte(int value) {
            if (value < SByte.MinValue || value > SByte.MaxValue) ThrowSByteOverflowException();
            Contract.EndContractBlock();
            return (sbyte)value;
        }

        [CLSCompliant(false)]   
        public static sbyte ToSByte(uint value) {
            if (value > SByte.MaxValue) ThrowSByteOverflowException();
            Contract.EndContractBlock();
            return (sbyte)value;
        }

        [CLSCompliant(false)]
        public static sbyte ToSByte(long value) {
            if (value < SByte.MinValue || value > SByte.MaxValue) ThrowSByteOverflowException();
            Contract.EndContractBlock();
            return (sbyte)value;
        }

        [CLSCompliant(false)]   
        public static sbyte ToSByte(ulong value) {
            if (value > (ulong)SByte.MaxValue) ThrowSByteOverflowException();
            Contract.EndContractBlock();
            return (sbyte)value;
        }

        [CLSCompliant(false)]
        public static sbyte ToSByte(float value) {
            return ToSByte((double)value);
        }

        [CLSCompliant(false)]
        public static sbyte ToSByte(double value) {
            return ToSByte(ToInt32(value));
        }

        [CLSCompliant(false)]
        public static sbyte ToSByte(decimal value) {
            return Decimal.ToSByte(Decimal.Round(value, 0));
        }

        [CLSCompliant(false)]
        public static sbyte ToSByte(String value) {
            if (value == null)
                return 0;
            return SByte.Parse(value, CultureInfo.CurrentCulture);
        }

        [CLSCompliant(false)]
        public static sbyte ToSByte(String value, IFormatProvider provider) {
            return SByte.Parse(value, NumberStyles.Integer, provider);
        }

        [CLSCompliant(false)]
        public static sbyte ToSByte(DateTime value)
        {
            return ((IConvertible)value).ToSByte(null);
        }

        // Disallowed conversions to SByte
        // public static sbyte ToSByte(TimeSpan value)

        // Conversions to Byte

        public static byte ToByte(object value) {
            return value == null? (byte)0: ((IConvertible)value).ToByte(null);
        }

        public static byte ToByte(object value, IFormatProvider provider) {
            return value == null? (byte)0: ((IConvertible)value).ToByte(provider);
        }

        public static byte ToByte(bool value) {
            return value? (byte)Boolean.True: (byte)Boolean.False;
        }

        public static byte ToByte(byte value) {
            return value;
        }

        public static byte ToByte(char value) {
            if (value > Byte.MaxValue) ThrowByteOverflowException();
            Contract.EndContractBlock();
            return (byte)value;
        }

        [CLSCompliant(false)]
        public static byte ToByte(sbyte value) {
            if (value < Byte.MinValue) ThrowByteOverflowException();
            Contract.EndContractBlock();
            return (byte)value;
        }

        public static byte ToByte(short value) {
            if (value < Byte.MinValue || value > Byte.MaxValue) ThrowByteOverflowException();
            Contract.EndContractBlock();
            return (byte)value;
        }

        [CLSCompliant(false)]   
        public static byte ToByte(ushort value) {
            if (value > Byte.MaxValue) ThrowByteOverflowException();
            Contract.EndContractBlock();
            return (byte)value;
        }

        public static byte ToByte(int value) {
            if (value < Byte.MinValue || value > Byte.MaxValue) ThrowByteOverflowException();
            Contract.EndContractBlock();
            return (byte)value;
        }

        [CLSCompliant(false)]   
        public static byte ToByte(uint value) {
            if (value > Byte.MaxValue) ThrowByteOverflowException();
            Contract.EndContractBlock();
            return (byte)value;
        }

        public static byte ToByte(long value) {
            if (value < Byte.MinValue || value > Byte.MaxValue) ThrowByteOverflowException();
            Contract.EndContractBlock();
            return (byte)value;
        }

        [CLSCompliant(false)]   
        public static byte ToByte(ulong value) {
            if (value > Byte.MaxValue) ThrowByteOverflowException();
            Contract.EndContractBlock();
            return (byte)value;
        }

        public static byte ToByte(float value) {
            return ToByte((double)value);
        }

        public static byte ToByte(double value) {
            return ToByte(ToInt32(value));
        }

        public static byte ToByte(decimal value) {
            return Decimal.ToByte(Decimal.Round(value, 0));
        }

        public static byte ToByte(String value) {
            if (value == null)
                return 0;
            return Byte.Parse(value, CultureInfo.CurrentCulture);
        }

        public static byte ToByte(String value, IFormatProvider provider) {
            if (value == null)
                return 0;
            return Byte.Parse(value, NumberStyles.Integer, provider);
        }

        public static byte ToByte(DateTime value)
        {
            return ((IConvertible)value).ToByte(null);
        }


        // Disallowed conversions to Byte
        // public static byte ToByte(TimeSpan value)

        // Conversions to Int16

        public static short ToInt16(object value) {
            return value == null? (short)0: ((IConvertible)value).ToInt16(null);
        }

        public static short ToInt16(object value, IFormatProvider provider) {
            return value == null? (short)0: ((IConvertible)value).ToInt16(provider);
        }

        public static short ToInt16(bool value) {
            return value? (short)Boolean.True: (short)Boolean.False;
        }

        public static short ToInt16(char value) {
            if (value > Int16.MaxValue) ThrowInt16OverflowException();
            Contract.EndContractBlock();
            return (short)value;
        }

        [CLSCompliant(false)]
        public static short ToInt16(sbyte value) {
            return value;
        }

        public static short ToInt16(byte value) {
            return value;
        }

        [CLSCompliant(false)]   
        public static short ToInt16(ushort value) {
            if (value > Int16.MaxValue) ThrowInt16OverflowException();
            Contract.EndContractBlock();
            return (short)value;
        }

        public static short ToInt16(int value) {
            if (value < Int16.MinValue || value > Int16.MaxValue) ThrowInt16OverflowException();
            Contract.EndContractBlock();
            return (short)value;
        }

        [CLSCompliant(false)]   
        public static short ToInt16(uint value) {
            if (value > Int16.MaxValue) ThrowInt16OverflowException();
            Contract.EndContractBlock();
            return (short)value;
        }

        public static short ToInt16(short value) {
            return value;
        }

        public static short ToInt16(long value) {
            if (value < Int16.MinValue || value > Int16.MaxValue) ThrowInt16OverflowException();
            Contract.EndContractBlock();
            return (short)value;
        }

        [CLSCompliant(false)]   
        public static short ToInt16(ulong value) {
            if (value > (ulong)Int16.MaxValue) ThrowInt16OverflowException();
            Contract.EndContractBlock();
            return (short)value;
        }

        public static short ToInt16(float value) {
            return ToInt16((double)value);
        }

        public static short ToInt16(double value) {
            return ToInt16(ToInt32(value));
        }

        public static short ToInt16(decimal value) {
            return Decimal.ToInt16(Decimal.Round(value, 0));
        }

        public static short ToInt16(String value) {
            if (value == null)
                return 0;
            return Int16.Parse(value, CultureInfo.CurrentCulture);
        }

        public static short ToInt16(String value, IFormatProvider provider) {
            if (value == null)
                return 0;
            return Int16.Parse(value, NumberStyles.Integer, provider);
        }

        public static short ToInt16(DateTime value)
        {
            return ((IConvertible)value).ToInt16(null);
        }


        // Disallowed conversions to Int16
        // public static short ToInt16(TimeSpan value)

        // Conversions to UInt16

        [CLSCompliant(false)]   
        public static ushort ToUInt16(object value) {
            return value == null? (ushort)0: ((IConvertible)value).ToUInt16(null);
        }

        [CLSCompliant(false)]   
        public static ushort ToUInt16(object value, IFormatProvider provider) {
            return value == null? (ushort)0: ((IConvertible)value).ToUInt16(provider);
        }


        [CLSCompliant(false)]   
        public static ushort ToUInt16(bool value) {
            return value? (ushort)Boolean.True: (ushort)Boolean.False;
        }

        [CLSCompliant(false)]   
        public static ushort ToUInt16(char value) {
            return value;
        }

        [CLSCompliant(false)]   
        public static ushort ToUInt16(sbyte value) {
            if (value < 0) ThrowUInt16OverflowException();
            Contract.EndContractBlock();
            return (ushort)value;
        }

        [CLSCompliant(false)]   
        public static ushort ToUInt16(byte value) {
            return value;
        }

        [CLSCompliant(false)]   
        public static ushort ToUInt16(short value) {
            if (value < 0) ThrowUInt16OverflowException();
            Contract.EndContractBlock();
            return (ushort)value;
        }

        [CLSCompliant(false)]   
        public static ushort ToUInt16(int value) {
            if (value < 0 || value > UInt16.MaxValue) ThrowUInt16OverflowException();
            Contract.EndContractBlock();
            return (ushort)value;
        }

        [CLSCompliant(false)] 
        public static ushort ToUInt16(ushort value) {
            return value;
        }

        [CLSCompliant(false)]   
        public static ushort ToUInt16(uint value) {
            if (value > UInt16.MaxValue) ThrowUInt16OverflowException();
            Contract.EndContractBlock();
            return (ushort)value;
        }

        
        [CLSCompliant(false)]   
        public static ushort ToUInt16(long value) {
            if (value < 0 || value > UInt16.MaxValue) ThrowUInt16OverflowException();
            Contract.EndContractBlock();
            return (ushort)value;
        }

        [CLSCompliant(false)]   
        public static ushort ToUInt16(ulong value) {
            if (value > UInt16.MaxValue) ThrowUInt16OverflowException();
            Contract.EndContractBlock();
            return (ushort)value;
        }

        [CLSCompliant(false)]   
        public static ushort ToUInt16(float value) {
            return ToUInt16((double)value);
        }

        [CLSCompliant(false)]   
        public static ushort ToUInt16(double value) {
            return ToUInt16(ToInt32(value));
        }

        [CLSCompliant(false)]   
        public static ushort ToUInt16(decimal value) {
            return Decimal.ToUInt16(Decimal.Round(value, 0));
        }

        [CLSCompliant(false)]   
        public static ushort ToUInt16(String value) {
            if (value == null)
                return 0;
            return UInt16.Parse(value, CultureInfo.CurrentCulture);
        }

        [CLSCompliant(false)]
        public static ushort ToUInt16(String value, IFormatProvider provider) {
            if (value == null)
                return 0;
            return UInt16.Parse(value, NumberStyles.Integer, provider);
        }

        [CLSCompliant(false)]
        public static ushort ToUInt16(DateTime value)
        {
            return ((IConvertible)value).ToUInt16(null);
        }

        // Disallowed conversions to UInt16
        // public static ushort ToUInt16(TimeSpan value)

        // Conversions to Int32

        public static int ToInt32(object value) {
            return value == null? 0: ((IConvertible)value).ToInt32(null);
        }

        public static int ToInt32(object value, IFormatProvider provider) {
            return value == null? 0: ((IConvertible)value).ToInt32(provider);
        }


        public static int ToInt32(bool value) {
            return value? Boolean.True: Boolean.False;
        }

        public static int ToInt32(char value) {
            return value;
        }

        [CLSCompliant(false)]
        public static int ToInt32(sbyte value) {
            return value;
        }

        public static int ToInt32(byte value) {
            return value;
        }

        public static int ToInt32(short value) {
            return value;
        }

        [CLSCompliant(false)]   
        public static int ToInt32(ushort value) {
            return value;
        }

        [CLSCompliant(false)]   
        public static int ToInt32(uint value) {
            if (value > Int32.MaxValue) ThrowInt32OverflowException();
            Contract.EndContractBlock();
            return (int)value;
        }

        public static int ToInt32(int value) {
            return value;
        }

        public static int ToInt32(long value) {
            if (value < Int32.MinValue || value > Int32.MaxValue) ThrowInt32OverflowException();
            Contract.EndContractBlock();
            return (int)value;
        }

        [CLSCompliant(false)]   
        public static int ToInt32(ulong value) {
            if (value > Int32.MaxValue) ThrowInt32OverflowException();
            Contract.EndContractBlock();
            return (int)value;
        }

        public static int ToInt32(float value) {
            return ToInt32((double)value);
        }

        public static int ToInt32(double value) {
            if (value >= 0) {
                if (value < 2147483647.5) {
                    int result = (int)value;
                    double dif = value - result;
                    if (dif > 0.5 || dif == 0.5 && (result & 1) != 0) result++;
                    return result;
                }
            }
            else {
                if (value >= -2147483648.5) {
                    int result = (int)value;
                    double dif = value - result;
                    if (dif < -0.5 || dif == -0.5 && (result & 1) != 0) result--;
                    return result;
                }
            }
            throw new OverflowException(Environment.GetResourceString("Overflow_Int32"));
        }

        [System.Security.SecuritySafeCritical]  // auto-generated
        public static int ToInt32(decimal value) {
            return Decimal.FCallToInt32(value);
        }

        public static int ToInt32(String value) {
            if (value == null)
                return 0;
            return Int32.Parse(value, CultureInfo.CurrentCulture);
        }

        public static int ToInt32(String value, IFormatProvider provider) {
            if (value == null)
                return 0;
            return Int32.Parse(value, NumberStyles.Integer, provider);
        }

        public static int ToInt32(DateTime value)
        {
            return ((IConvertible)value).ToInt32(null);
        }


        // Disallowed conversions to Int32
        // public static int ToInt32(TimeSpan value)

        // Conversions to UInt32

        [CLSCompliant(false)]   
        public static uint ToUInt32(object value) {
            return value == null? 0: ((IConvertible)value).ToUInt32(null);
        }

        [CLSCompliant(false)]   
        public static uint ToUInt32(object value, IFormatProvider provider) {
            return value == null? 0: ((IConvertible)value).ToUInt32(provider);
        }


        [CLSCompliant(false)]   
        public static uint ToUInt32(bool value) {
            return value? (uint)Boolean.True: (uint)Boolean.False;
        }

        [CLSCompliant(false)]   
        public static uint ToUInt32(char value) {
            return value;
        }

        [CLSCompliant(false)]   
        public static uint ToUInt32(sbyte value) {
            if (value < 0) ThrowUInt32OverflowException();
            Contract.EndContractBlock();
            return (uint)value;
        }

        [CLSCompliant(false)]   
        public static uint ToUInt32(byte value) {
            return value;
        }

        [CLSCompliant(false)]   
        public static uint ToUInt32(short value) {
            if (value < 0) ThrowUInt32OverflowException();
            Contract.EndContractBlock();
            return (uint)value;
        }

        [CLSCompliant(false)]   
        public static uint ToUInt32(ushort value) {
            return value;
        }

        [CLSCompliant(false)]   
        public static uint ToUInt32(int value) {
            if (value < 0) ThrowUInt32OverflowException();
            Contract.EndContractBlock();
            return (uint)value;
        }

        [CLSCompliant(false)] 
        public static uint ToUInt32(uint value) {
            return value;
        }

        [CLSCompliant(false)]   
        public static uint ToUInt32(long value) {
            if (value < 0 || value > UInt32.MaxValue) ThrowUInt32OverflowException();
            Contract.EndContractBlock();
            return (uint)value;
        }

        [CLSCompliant(false)]   
        public static uint ToUInt32(ulong value) {
            if (value > UInt32.MaxValue) ThrowUInt32OverflowException();
            Contract.EndContractBlock();
            return (uint)value;
        }

        [CLSCompliant(false)]   
        public static uint ToUInt32(float value) {
            return ToUInt32((double)value);
        }

        [CLSCompliant(false)]   
        public static uint ToUInt32(double value) {
            if (value >= -0.5 && value < 4294967295.5) {
                uint result = (uint)value;
                double dif = value - result;
                if (dif > 0.5 || dif == 0.5 && (result & 1) != 0) result++;
                return result;
            }
            throw new OverflowException(Environment.GetResourceString("Overflow_UInt32"));
        }

        [CLSCompliant(false)]   
        public static uint ToUInt32(decimal value) {
            return Decimal.ToUInt32(Decimal.Round(value, 0));
        }

        [CLSCompliant(false)]   
        public static uint ToUInt32(String value) {
            if (value == null)
                return 0;
            return UInt32.Parse(value, CultureInfo.CurrentCulture);
        }

        [CLSCompliant(false)]
        public static uint ToUInt32(String value, IFormatProvider provider) {
            if (value == null)
                return 0;
            return UInt32.Parse(value, NumberStyles.Integer, provider);
        }

        [CLSCompliant(false)]
        public static uint ToUInt32(DateTime value)
        {
            return ((IConvertible)value).ToUInt32(null);
        }

        // Disallowed conversions to UInt32
        // public static uint ToUInt32(TimeSpan value)

        // Conversions to Int64

        public static long ToInt64(object value) {
            return value == null? 0: ((IConvertible)value).ToInt64(null);
        }

        public static long ToInt64(object value, IFormatProvider provider) {
            return value == null? 0: ((IConvertible)value).ToInt64(provider);
        }


        public static long ToInt64(bool value) {
            return value? Boolean.True: Boolean.False;
        }

        public static long ToInt64(char value) {
            return value;
        }

        [CLSCompliant(false)]
        public static long ToInt64(sbyte value) {
            return value;
        }

        public static long ToInt64(byte value) {
            return value;
        }

        public static long ToInt64(short value) {
            return value;
        }

        [CLSCompliant(false)]   
        public static long ToInt64(ushort value) {
            return value;
        }

        public static long ToInt64(int value) {
            return value;
        }

        [CLSCompliant(false)]   
        public static long ToInt64(uint value) {
            return value;
        }

        [CLSCompliant(false)]   
        public static long ToInt64(ulong value) {
            if (value > Int64.MaxValue) ThrowInt64OverflowException();
            Contract.EndContractBlock();
            return (long)value;
        }

        public static long ToInt64(long value) {
            return value;
        }


        public static long ToInt64(float value) {
            return ToInt64((double)value);
        }

        public static long ToInt64(double value) {
            return checked((long)Math.Round(value));
        }

        public static long ToInt64(decimal value) {
            return Decimal.ToInt64(Decimal.Round(value, 0));
        }

        public static long ToInt64(string value) {
            if (value == null)
                return 0;
            return Int64.Parse(value, CultureInfo.CurrentCulture);
        }

        public static long ToInt64(String value, IFormatProvider provider) {
            if (value == null)
                return 0;
            return Int64.Parse(value, NumberStyles.Integer, provider);
        }

        public static long ToInt64(DateTime value)
        {
            return ((IConvertible)value).ToInt64(null);
        }

        // Disallowed conversions to Int64
        // public static long ToInt64(TimeSpan value)

        // Conversions to UInt64

        [CLSCompliant(false)]   
        public static ulong ToUInt64(object value) {
            return value == null? 0: ((IConvertible)value).ToUInt64(null);
        }

        [CLSCompliant(false)]   
        public static ulong ToUInt64(object value, IFormatProvider provider) {
            return value == null? 0: ((IConvertible)value).ToUInt64(provider);
        }

        [CLSCompliant(false)]   
        public static ulong ToUInt64(bool value) {
            return value? (ulong)Boolean.True: (ulong)Boolean.False;
        }

        [CLSCompliant(false)]   
        public static ulong ToUInt64(char value) {
            return value;
        }

    
        [CLSCompliant(false)]   
        public static ulong ToUInt64(sbyte value) {
            if (value < 0) ThrowUInt64OverflowException();
            Contract.EndContractBlock();
            return (ulong)value;
        }

        [CLSCompliant(false)]   
        public static ulong ToUInt64(byte value) {
            return value;
        }

        [CLSCompliant(false)]   
        public static ulong ToUInt64(short value) {
            if (value < 0) ThrowUInt64OverflowException();
            Contract.EndContractBlock();
            return (ulong)value;
        }

        [CLSCompliant(false)]   
        public static ulong ToUInt64(ushort value) {
            return value;
        }

        [CLSCompliant(false)]   
        public static ulong ToUInt64(int value) {
            if (value < 0) ThrowUInt64OverflowException();
            Contract.EndContractBlock();
            return (ulong)value;
        }

        [CLSCompliant(false)]   
        public static ulong ToUInt64(uint value) {
            return value;
        }

        [CLSCompliant(false)]   
        public static ulong ToUInt64(long value) {
            if (value < 0) ThrowUInt64OverflowException();
            Contract.EndContractBlock();
            return (ulong)value;
        }

        [CLSCompliant(false)]   
        public static ulong ToUInt64(UInt64 value) {
            return value;
        }

        [CLSCompliant(false)]   
        public static ulong ToUInt64(float value) {
            return ToUInt64((double)value);
        }

        [CLSCompliant(false)]   
        public static ulong ToUInt64(double value) {
            return checked((ulong)Math.Round(value));
        }

        [CLSCompliant(false)]   
        public static ulong ToUInt64(decimal value) {
            return Decimal.ToUInt64(Decimal.Round(value, 0));
        }

        [CLSCompliant(false)]   
        public static ulong ToUInt64(String value) {
            if (value == null)
                return 0;
            return UInt64.Parse(value, CultureInfo.CurrentCulture);
        }

        [CLSCompliant(false)]
        public static ulong ToUInt64(String value, IFormatProvider provider) {
            if (value == null)
                return 0;
            return UInt64.Parse(value, NumberStyles.Integer, provider);
        }

        [CLSCompliant(false)]
        public static ulong ToUInt64(DateTime value)
        {
            return ((IConvertible)value).ToUInt64(null);
        }

        // Disallowed conversions to UInt64
        // public static ulong ToUInt64(TimeSpan value)

        // Conversions to Single

        public static float ToSingle(object value) {
            return value == null? 0: ((IConvertible)value).ToSingle(null);
        }

        public static float ToSingle(object value, IFormatProvider provider) {
            return value == null? 0: ((IConvertible)value).ToSingle(provider);
        }

        [CLSCompliant(false)]
        public static float ToSingle(sbyte value) {
            return value;
        }

        public static float ToSingle(byte value) {
            return value;
        }

        public static float ToSingle(char value) {
            return ((IConvertible)value).ToSingle(null);
        }

        public static float ToSingle(short value) {
            return value;
        }

        [CLSCompliant(false)]   
        public static float ToSingle(ushort value) {
            return value;
        }

        public static float ToSingle(int value) {
            return value;
        }

        [CLSCompliant(false)]   
        public static float ToSingle(uint value) {
            return value;
        }

        public static float ToSingle(long value) {
            return value;
        }

        [CLSCompliant(false)]   
        public static float ToSingle(ulong value) {
            return value;
        }

        public static float ToSingle(float value) {
            return value;
        }

        public static float ToSingle(double value) {
            return (float)value;
        }

        public static float ToSingle(decimal value) {
            return (float)value;
        }

        public static float ToSingle(String value) {
            if (value == null)
                return 0;
            return Single.Parse(value, CultureInfo.CurrentCulture);
        }

        public static float ToSingle(String value, IFormatProvider provider) {
            if (value == null)
                return 0;
            return Single.Parse(value, NumberStyles.Float | NumberStyles.AllowThousands, provider);
        }


        public static float ToSingle(bool value)
        {
            return value? Boolean.True: Boolean.False;
        }

        public static float ToSingle(DateTime value)
        {
            return ((IConvertible)value).ToSingle(null);
        }

        // Disallowed conversions to Single
        // public static float ToSingle(TimeSpan value)

        // Conversions to Double

        public static double ToDouble(object value) {
            return value == null? 0: ((IConvertible)value).ToDouble(null);
        }

        public static double ToDouble(object value, IFormatProvider provider) {
            return value == null? 0: ((IConvertible)value).ToDouble(provider);
        }


        [CLSCompliant(false)]
        public static double ToDouble(sbyte value) {
            return value;
        }

        public static double ToDouble(byte value) {
            return value;
        }

        public static double ToDouble(short value) {
            return value;
        }

        public static double ToDouble(char value) {
            return ((IConvertible)value).ToDouble(null);
        }

        [CLSCompliant(false)]   
        public static double ToDouble(ushort value) {
            return value;
        }

        public static double ToDouble(int value) {
            return value;
        }

        [CLSCompliant(false)]   
        public static double ToDouble(uint value) {
            return value;
        }

        public static double ToDouble(long value) {
            return value;
        }

        [CLSCompliant(false)]   
        public static double ToDouble(ulong value) {
            return value;
        }

        public static double ToDouble(float value) {
            return value;
        }

        public static double ToDouble(double value) {
            return value;
        }

        public static double ToDouble(decimal value) {
            return (double)value;
        }

        public static double ToDouble(String value) {
            if (value == null)
                return 0;
            return Double.Parse(value, CultureInfo.CurrentCulture);
        }

        public static double ToDouble(String value, IFormatProvider provider) {
            if (value == null)
                return 0;
            return Double.Parse(value, NumberStyles.Float | NumberStyles.AllowThousands, provider);
        }

        public static double ToDouble(bool value) {
            return value? Boolean.True: Boolean.False;
        }

        public static double ToDouble(DateTime value)
        {
            return ((IConvertible)value).ToDouble(null);
        }

        // Disallowed conversions to Double
        // public static double ToDouble(TimeSpan value)

        // Conversions to Decimal

        public static decimal ToDecimal(object value) {
            return value == null? 0: ((IConvertible)value).ToDecimal(null);
        }

        public static decimal ToDecimal(object value, IFormatProvider provider) {
            return value == null? 0: ((IConvertible)value).ToDecimal(provider);
        }

        [CLSCompliant(false)]
        public static decimal ToDecimal(sbyte value) {
            return value;
        }

        public static decimal ToDecimal(byte value) {
            return value;
        }

        public static decimal ToDecimal(char value) {
            return ((IConvertible)value).ToDecimal(null);
        }

        public static decimal ToDecimal(short value) {
            return value;
        }

        [CLSCompliant(false)]   
        public static decimal ToDecimal(ushort value) {
            return value;
        }

        public static decimal ToDecimal(int value) {
            return value;
        }

        [CLSCompliant(false)]   
        public static decimal ToDecimal(uint value) {
            return value;
        }

        public static decimal ToDecimal(long value) {
            return value;
        }

        [CLSCompliant(false)]   
        public static decimal ToDecimal(ulong value) {
            return value;
        }

        public static decimal ToDecimal(float value) {
            return (decimal)value;
        }

        public static decimal ToDecimal(double value) {
            return (decimal)value;
        }

        public static decimal ToDecimal(String value) {
            if (value == null)
                return 0m;
            return Decimal.Parse(value, CultureInfo.CurrentCulture);
        }

        public static Decimal ToDecimal(String value, IFormatProvider provider) {
            if (value == null)
                return 0m;
            return Decimal.Parse(value, NumberStyles.Number, provider);
        }

        public static decimal ToDecimal(decimal value) {
            return value;
        }

        public static decimal ToDecimal(bool value) {
            return value? Boolean.True: Boolean.False;
        }

        public static decimal ToDecimal(DateTime value)
        {
            return ((IConvertible)value).ToDecimal(null);
        }

        // Disallowed conversions to Decimal
        // public static decimal ToDecimal(TimeSpan value)

        // Conversions to DateTime

        public static DateTime ToDateTime(DateTime value) {
            return value;
        }

        public static DateTime ToDateTime(object value) {
            return value == null? DateTime.MinValue: ((IConvertible)value).ToDateTime(null);
        }

        public static DateTime ToDateTime(object value, IFormatProvider provider) {
            return value == null? DateTime.MinValue: ((IConvertible)value).ToDateTime(provider);
        }

        public static DateTime ToDateTime(String value) {
            if (value == null)
                return new DateTime(0);
            return DateTime.Parse(value, CultureInfo.CurrentCulture);
        }

        public static DateTime ToDateTime(String value, IFormatProvider provider) {
            if (value == null)
                return new DateTime(0);
            return DateTime.Parse(value, provider);
        }

         [CLSCompliant(false)]
        public static DateTime ToDateTime(sbyte value) {
            return ((IConvertible)value).ToDateTime(null);
        }

        public static DateTime ToDateTime(byte value) {
            return ((IConvertible)value).ToDateTime(null);
        }

        public static DateTime ToDateTime(short value) {
            return ((IConvertible)value).ToDateTime(null);
        }

        [CLSCompliant(false)]
        public static DateTime ToDateTime(ushort value) {
            return ((IConvertible)value).ToDateTime(null);
        }

        public static DateTime ToDateTime(int value) {
            return ((IConvertible)value).ToDateTime(null);
        }

        [CLSCompliant(false)]
        public static DateTime ToDateTime(uint value) {
            return ((IConvertible)value).ToDateTime(null);
        }

        public static DateTime ToDateTime(long value) {
            return ((IConvertible)value).ToDateTime(null);
        }

        [CLSCompliant(false)]
        public static DateTime ToDateTime(ulong value) {
            return ((IConvertible)value).ToDateTime(null);
        }

        public static DateTime ToDateTime(bool value) {
            return ((IConvertible)value).ToDateTime(null);
        }

        public static DateTime ToDateTime(char value) {
            return ((IConvertible)value).ToDateTime(null);
        }

        public static DateTime ToDateTime(float value) {
            return ((IConvertible)value).ToDateTime(null);
        }

        public static DateTime ToDateTime(double value) {
            return ((IConvertible)value).ToDateTime(null);
        }

        public static DateTime ToDateTime(decimal value) {
            return ((IConvertible)value).ToDateTime(null);
        }

        // Disallowed conversions to DateTime
        // public static DateTime ToDateTime(TimeSpan value)

        // Conversions to String

        public static string ToString(Object value) {
            return ToString(value,null);
        }

        public static string ToString(Object value, IFormatProvider provider) {
            IConvertible ic = value as IConvertible;
            if (ic != null) 
                return ic.ToString(provider);
            IFormattable formattable = value as IFormattable;
            if (formattable != null) 
                return formattable.ToString(null, provider);
            return value == null? String.Empty: value.ToString();
        }

        public static string ToString(bool value) {
            Contract.Ensures(Contract.Result<string>() != null);
            return value.ToString();
        }

        public static string ToString(bool value, IFormatProvider provider) {
            Contract.Ensures(Contract.Result<string>() != null);
            return value.ToString(provider);
        }

        public static string ToString(char value) {
            Contract.Ensures(Contract.Result<string>() != null);
            return Char.ToString(value);
        }

        public static string ToString(char value, IFormatProvider provider) {
            Contract.Ensures(Contract.Result<string>() != null);
            return value.ToString(provider);
        }

        [CLSCompliant(false)]
        public static string ToString(sbyte value) {
            Contract.Ensures(Contract.Result<string>() != null);
            return value.ToString(CultureInfo.CurrentCulture);
        }

        [CLSCompliant(false)]
        public static string ToString(sbyte value, IFormatProvider provider) {
            Contract.Ensures(Contract.Result<string>() != null);
            return value.ToString(provider);
        }

        public static string ToString(byte value) {
            Contract.Ensures(Contract.Result<string>() != null);
            return value.ToString(CultureInfo.CurrentCulture);
        }

        public static string ToString(byte value, IFormatProvider provider) {
            Contract.Ensures(Contract.Result<string>() != null);
            return value.ToString(provider);
        }

        public static string ToString(short value) {
            Contract.Ensures(Contract.Result<string>() != null);
            return value.ToString(CultureInfo.CurrentCulture);
        }

        public static string ToString(short value, IFormatProvider provider) {
            Contract.Ensures(Contract.Result<string>() != null);
            return value.ToString(provider);
        }

        [CLSCompliant(false)]   
        public static string ToString(ushort value) {
            Contract.Ensures(Contract.Result<string>() != null);
            return value.ToString(CultureInfo.CurrentCulture);
        }

        [CLSCompliant(false)]
        public static string ToString(ushort value, IFormatProvider provider) {
            Contract.Ensures(Contract.Result<string>() != null);
            return value.ToString(provider);
        }

        public static string ToString(int value) {
            Contract.Ensures(Contract.Result<string>() != null);
            return value.ToString(CultureInfo.CurrentCulture);
        }

        public static string ToString(int value, IFormatProvider provider) {
            Contract.Ensures(Contract.Result<string>() != null);
            return value.ToString(provider);
        }

        [CLSCompliant(false)]   
        public static string ToString(uint value) {
            Contract.Ensures(Contract.Result<string>() != null);
            return value.ToString(CultureInfo.CurrentCulture);
        }

        [CLSCompliant(false)]
        public static string ToString(uint value, IFormatProvider provider) {
            Contract.Ensures(Contract.Result<string>() != null);
            return value.ToString(provider);
        }

        public static string ToString(long value) {
            Contract.Ensures(Contract.Result<string>() != null);
            return value.ToString(CultureInfo.CurrentCulture);
        }

        public static string ToString(long value, IFormatProvider provider) {
            Contract.Ensures(Contract.Result<string>() != null);
            return value.ToString(provider);
        }

        [CLSCompliant(false)]   
        public static string ToString(ulong value) {
            Contract.Ensures(Contract.Result<string>() != null);
            return value.ToString(CultureInfo.CurrentCulture);
        }

        [CLSCompliant(false)]
        public static string ToString(ulong value, IFormatProvider provider) {
            Contract.Ensures(Contract.Result<string>() != null);
            return value.ToString(provider);
        }

        public static string ToString(float value) {
            Contract.Ensures(Contract.Result<string>() != null);
            return value.ToString(CultureInfo.CurrentCulture);
        }

        public static string ToString(float value, IFormatProvider provider) {
            Contract.Ensures(Contract.Result<string>() != null);
            return value.ToString(provider);
        }

        public static string ToString(double value) {
            Contract.Ensures(Contract.Result<string>() != null);
            return value.ToString(CultureInfo.CurrentCulture);
        }

        public static string ToString(double value, IFormatProvider provider) {
            Contract.Ensures(Contract.Result<string>() != null);
            return value.ToString(provider);
        }

        public static string ToString(decimal value) {
            Contract.Ensures(Contract.Result<string>() != null);
            return value.ToString(CultureInfo.CurrentCulture);
        }

        public static string ToString(Decimal value, IFormatProvider provider) {
            Contract.Ensures(Contract.Result<string>() != null);
            return value.ToString(provider);
        }

        public static string ToString(DateTime value) {
            Contract.Ensures(Contract.Result<string>() != null);
            return value.ToString();
        }

        public static string ToString(DateTime value, IFormatProvider provider) {
            Contract.Ensures(Contract.Result<string>() != null);
            return value.ToString(provider);
        }

        public static String ToString(String value) {
            Contract.Ensures(Contract.Result<string>() == value);  // We were always skipping the null check here.
            return value;
        }

        public static String ToString(String value,IFormatProvider provider) {
            Contract.Ensures(Contract.Result<string>() == value);  // We were always skipping the null check here.
            return value; // avoid the null check
        }


        //
        // Conversions which understand Base XXX numbers.
        //
        // Parses value in base base.  base can only
        // be 2, 8, 10, or 16.  If base is 16, the number may be preceded
        // by 0x; any other leading or trailing characters cause an error.
        //
        public static byte ToByte (String value, int fromBase) {
            if (fromBase!=2 && fromBase!=8 && fromBase!=10 && fromBase!=16) {
                throw new ArgumentException(Environment.GetResourceString("Arg_InvalidBase"));
            }
            Contract.EndContractBlock();
            int r = ParseNumbers.StringToInt(value,fromBase,ParseNumbers.IsTight | ParseNumbers.TreatAsUnsigned);
            if (r < Byte.MinValue || r > Byte.MaxValue)
                ThrowByteOverflowException();
            return (byte) r;
        }

        // Parses value in base fromBase.  fromBase can only
        // be 2, 8, 10, or 16.  If fromBase is 16, the number may be preceded
        // by 0x; any other leading or trailing characters cause an error.
        //
        [CLSCompliant(false)]
        public static sbyte ToSByte (String value, int fromBase) {
            if (fromBase!=2 && fromBase!=8 && fromBase!=10 && fromBase!=16) {
                throw new ArgumentException(Environment.GetResourceString("Arg_InvalidBase"));
            }
            Contract.EndContractBlock();
            int r = ParseNumbers.StringToInt(value,fromBase,ParseNumbers.IsTight | ParseNumbers.TreatAsI1);
            if (fromBase != 10 && r <= Byte.MaxValue)
                return (sbyte)r;

            if (r < SByte.MinValue || r > SByte.MaxValue)
                ThrowSByteOverflowException();
            return (sbyte) r;
        }

        // Parses value in base fromBase.  fromBase can only
        // be 2, 8, 10, or 16.  If fromBase is 16, the number may be preceded
        // by 0x; any other leading or trailing characters cause an error.
        //
        public static short ToInt16 (String value, int fromBase) {
            if (fromBase!=2 && fromBase!=8 && fromBase!=10 && fromBase!=16) {
                throw new ArgumentException(Environment.GetResourceString("Arg_InvalidBase"));
            }
            Contract.EndContractBlock();
            int r = ParseNumbers.StringToInt(value,fromBase,ParseNumbers.IsTight | ParseNumbers.TreatAsI2);
            if (fromBase != 10 && r <= UInt16.MaxValue)
                return (short)r;

            if (r < Int16.MinValue || r > Int16.MaxValue)
                ThrowInt16OverflowException();
            return (short) r;
        }

        // Parses value in base fromBase.  fromBase can only
        // be 2, 8, 10, or 16.  If fromBase is 16, the number may be preceded
        // by 0x; any other leading or trailing characters cause an error.
        //
        [CLSCompliant(false)]
        public static ushort ToUInt16 (String value, int fromBase) {
            if (fromBase!=2 && fromBase!=8 && fromBase!=10 && fromBase!=16) {
                throw new ArgumentException(Environment.GetResourceString("Arg_InvalidBase"));
            }
            Contract.EndContractBlock();
            int r = ParseNumbers.StringToInt(value,fromBase,ParseNumbers.IsTight | ParseNumbers.TreatAsUnsigned);
            if (r < UInt16.MinValue || r > UInt16.MaxValue)
                ThrowUInt16OverflowException();
            return (ushort) r;
        }

        // Parses value in base fromBase.  fromBase can only
        // be 2, 8, 10, or 16.  If fromBase is 16, the number may be preceded
        // by 0x; any other leading or trailing characters cause an error.
        //
        public static int ToInt32 (String value, int fromBase) {
            if (fromBase!=2 && fromBase!=8 && fromBase!=10 && fromBase!=16) {
                throw new ArgumentException(Environment.GetResourceString("Arg_InvalidBase"));
            }
            Contract.EndContractBlock();
            return ParseNumbers.StringToInt(value,fromBase,ParseNumbers.IsTight);
        }

        // Parses value in base fromBase.  fromBase can only
        // be 2, 8, 10, or 16.  If fromBase is 16, the number may be preceded
        // by 0x; any other leading or trailing characters cause an error.
        //
        [CLSCompliant(false)]
        public static uint ToUInt32 (String value, int fromBase) {
            if (fromBase!=2 && fromBase!=8 && fromBase!=10 && fromBase!=16) {
                throw new ArgumentException(Environment.GetResourceString("Arg_InvalidBase"));
            }
            Contract.EndContractBlock();
            return (uint) ParseNumbers.StringToInt(value,fromBase, ParseNumbers.TreatAsUnsigned | ParseNumbers.IsTight);
        }

        // Parses value in base fromBase.  fromBase can only
        // be 2, 8, 10, or 16.  If fromBase is 16, the number may be preceded
        // by 0x; any other leading or trailing characters cause an error.
        //
        public static long ToInt64 (String value, int fromBase) {
            if (fromBase!=2 && fromBase!=8 && fromBase!=10 && fromBase!=16) {
                throw new ArgumentException(Environment.GetResourceString("Arg_InvalidBase"));
            }
            Contract.EndContractBlock();
            return ParseNumbers.StringToLong(value,fromBase,ParseNumbers.IsTight);
        }

        // Parses value in base fromBase.  fromBase can only
        // be 2, 8, 10, or 16.  If fromBase is 16, the number may be preceded
        // by 0x; any other leading or trailing characters cause an error.
        //
        [CLSCompliant(false)]
        public static ulong ToUInt64 (String value, int fromBase) {
            if (fromBase!=2 && fromBase!=8 && fromBase!=10 && fromBase!=16) {
                throw new ArgumentException(Environment.GetResourceString("Arg_InvalidBase"));
            }
            Contract.EndContractBlock();
            return (ulong) ParseNumbers.StringToLong(value,fromBase, ParseNumbers.TreatAsUnsigned | ParseNumbers.IsTight);
        }

        // Convert the byte value to a string in base fromBase
        [System.Security.SecuritySafeCritical]  // auto-generated
        public static String ToString (byte value, int toBase) {
            if (toBase!=2 && toBase!=8 && toBase!=10 && toBase!=16) {
                throw new ArgumentException(Environment.GetResourceString("Arg_InvalidBase"));
            }
            Contract.EndContractBlock();
            return ParseNumbers.IntToString((int)value, toBase, -1, ' ', ParseNumbers.PrintAsI1);
        }

        // Convert the Int16 value to a string in base fromBase
        [System.Security.SecuritySafeCritical]  // auto-generated
        public static String ToString (short value, int toBase) {
            if (toBase!=2 && toBase!=8 && toBase!=10 && toBase!=16) {
                throw new ArgumentException(Environment.GetResourceString("Arg_InvalidBase"));
            }
            Contract.EndContractBlock();
            return ParseNumbers.IntToString((int)value, toBase, -1, ' ', ParseNumbers.PrintAsI2);
        }

        // Convert the Int32 value to a string in base toBase
        [System.Security.SecuritySafeCritical]  // auto-generated
        public static String ToString (int value, int toBase) {
            if (toBase!=2 && toBase!=8 && toBase!=10 && toBase!=16) {
                throw new ArgumentException(Environment.GetResourceString("Arg_InvalidBase"));
            }
            Contract.EndContractBlock();
            return ParseNumbers.IntToString(value, toBase, -1, ' ', 0);
        }

        // Convert the Int64 value to a string in base toBase
        [System.Security.SecuritySafeCritical]  // auto-generated
        public static String ToString (long value, int toBase) {
            if (toBase!=2 && toBase!=8 && toBase!=10 && toBase!=16) {
                throw new ArgumentException(Environment.GetResourceString("Arg_InvalidBase"));
            }
            Contract.EndContractBlock();
            return ParseNumbers.LongToString(value, toBase, -1, ' ', 0);
        }

        public static String ToBase64String(byte[] inArray) {
            if (inArray==null) {
                throw new ArgumentNullException("inArray");
            }
            Contract.Ensures(Contract.Result<string>() != null);
            Contract.EndContractBlock();
            return ToBase64String(inArray, 0, inArray.Length, Base64FormattingOptions.None);
        }

        [System.Runtime.InteropServices.ComVisible(false)]
        public static String ToBase64String(byte[] inArray, Base64FormattingOptions options) {
            if (inArray==null) {
                throw new ArgumentNullException("inArray");
            }
            Contract.Ensures(Contract.Result<string>() != null);
            Contract.EndContractBlock();
            return ToBase64String(inArray, 0, inArray.Length, options);
        }

        public static String ToBase64String(byte[] inArray, int offset, int length) {
            return ToBase64String(inArray, offset, length, Base64FormattingOptions.None);
        }

        [System.Security.SecuritySafeCritical]  // auto-generated
        [System.Runtime.InteropServices.ComVisible(false)]
        public static unsafe String ToBase64String(byte[] inArray, int offset, int length, Base64FormattingOptions options) {
            //Do data verfication
            if (inArray==null) 
                throw new ArgumentNullException("inArray");
            if (length<0)
                throw new ArgumentOutOfRangeException("length", Environment.GetResourceString("ArgumentOutOfRange_Index"));
            if (offset<0)
                throw new ArgumentOutOfRangeException("offset", Environment.GetResourceString("ArgumentOutOfRange_GenericPositive"));
            if (options < Base64FormattingOptions.None || options > Base64FormattingOptions.InsertLineBreaks)
                throw new ArgumentException(Environment.GetResourceString("Arg_EnumIllegalVal", (int)options));
            Contract.Ensures(Contract.Result<string>() != null);
            Contract.EndContractBlock();

            int inArrayLength;
            int stringLength;

            inArrayLength = inArray.Length;
            if (offset > (inArrayLength - length))
                throw new ArgumentOutOfRangeException("offset", Environment.GetResourceString("ArgumentOutOfRange_OffsetLength"));
           
            if (inArrayLength == 0)
                return String.Empty;

            bool insertLineBreaks = (options == Base64FormattingOptions.InsertLineBreaks);
            //Create the new string.  This is the maximally required length.
            stringLength = ToBase64_CalculateAndValidateOutputLength(length, insertLineBreaks);

            string returnString = string.FastAllocateString(stringLength);
            fixed (char* outChars = returnString){
                fixed (byte* inData = inArray) {
                    int j = ConvertToBase64Array(outChars,inData,offset,length, insertLineBreaks);
                    BCLDebug.Assert(returnString.Length == j, "returnString.Length == j");
                    return returnString;
                }
            }
        }

        public static int ToBase64CharArray(byte[] inArray, int offsetIn, int length, char[] outArray, int offsetOut) {
            Contract.Ensures(Contract.Result<int>() >= 0);
            Contract.Ensures(Contract.Result<int>() <= outArray.Length);
            Contract.EndContractBlock();

            return ToBase64CharArray(inArray, offsetIn, length, outArray, offsetOut, Base64FormattingOptions.None);
        }
        
        [System.Security.SecuritySafeCritical]  // auto-generated
        [System.Runtime.InteropServices.ComVisible(false)]
        public static unsafe int ToBase64CharArray(byte[] inArray, int offsetIn, int length, char[] outArray, int offsetOut, Base64FormattingOptions options) {
            //Do data verfication
            if (inArray==null) 
                throw new ArgumentNullException("inArray");
            if (outArray==null)
                throw new ArgumentNullException("outArray");
            if (length<0)
                throw new ArgumentOutOfRangeException("length", Environment.GetResourceString("ArgumentOutOfRange_Index"));
            if (offsetIn<0)
                throw new ArgumentOutOfRangeException("offsetIn", Environment.GetResourceString("ArgumentOutOfRange_GenericPositive"));
            if (offsetOut<0)
                throw new ArgumentOutOfRangeException("offsetOut", Environment.GetResourceString("ArgumentOutOfRange_GenericPositive"));

            if( options < Base64FormattingOptions.None || options > Base64FormattingOptions.InsertLineBreaks) {
                throw new ArgumentException(Environment.GetResourceString("Arg_EnumIllegalVal", (int)options));
            }
            Contract.Ensures(Contract.Result<int>() >= 0);
            Contract.Ensures(Contract.Result<int>() <= outArray.Length);
            Contract.EndContractBlock();


            int retVal;

            int inArrayLength;
            int outArrayLength;
            int numElementsToCopy;

            inArrayLength = inArray.Length;

            if (offsetIn > (int)(inArrayLength - length))
                throw new ArgumentOutOfRangeException("offsetIn", Environment.GetResourceString("ArgumentOutOfRange_OffsetLength"));

            if (inArrayLength == 0)
                return 0;

            bool insertLineBreaks = (options == Base64FormattingOptions.InsertLineBreaks);
            //This is the maximally required length that must be available in the char array
            outArrayLength = outArray.Length;

            // Length of the char buffer required
            numElementsToCopy = ToBase64_CalculateAndValidateOutputLength(length, insertLineBreaks);
    
            if (offsetOut > (int)(outArrayLength -  numElementsToCopy))
                throw new ArgumentOutOfRangeException("offsetOut", Environment.GetResourceString("ArgumentOutOfRange_OffsetOut"));

            fixed (char* outChars = &outArray[offsetOut]) {
                fixed (byte* inData = inArray) { 
                   retVal = ConvertToBase64Array(outChars,inData,offsetIn,length, insertLineBreaks);
                }
            }

            return retVal;
        }

        [System.Security.SecurityCritical]  // auto-generated
        private static unsafe int ConvertToBase64Array(char* outChars, byte* inData, int offset, int length, bool insertLineBreaks) {
            int lengthmod3 = length%3;
            int calcLength = offset + (length - lengthmod3);
            int j=0;
            int charcount = 0;
            //Convert three bytes at a time to base64 notation.  This will consume 4 chars.
            int i;

            // get a pointer to the base64Table to avoid unnecessary range checking
            fixed(char* base64 = base64Table) {
                for (i=offset; i<calcLength; i+=3)
                {
                    if (insertLineBreaks) {
                        if (charcount == base64LineBreakPosition) {
                            outChars[j++] = '\r';
                            outChars[j++] = '\n';
                            charcount = 0;
                        }
                        charcount += 4;
                    }
                    outChars[j] = base64[(inData[i]&0xfc)>>2];
                    outChars[j+1] = base64[((inData[i]&0x03)<<4) | ((inData[i+1]&0xf0)>>4)];
                    outChars[j+2] = base64[((inData[i+1]&0x0f)<<2) | ((inData[i+2]&0xc0)>>6)];
                    outChars[j+3] = base64[(inData[i+2]&0x3f)];
                    j += 4;
                }

                //Where we left off before
                i =  calcLength;

                if (insertLineBreaks && (lengthmod3 !=0) && (charcount == base64LineBreakPosition)) {
                    outChars[j++] = '\r';
                    outChars[j++] = '\n';
                }
                    
                switch(lengthmod3)
                {
                case 2: //One character padding needed
                    outChars[j] = base64[(inData[i]&0xfc)>>2];
                    outChars[j+1] = base64[((inData[i]&0x03)<<4)|((inData[i+1]&0xf0)>>4)];
                    outChars[j+2] = base64[(inData[i+1]&0x0f)<<2];
                    outChars[j+3] = base64[64]; //Pad
                    j+=4;
                    break;
                case 1: // Two character padding needed
                    outChars[j] = base64[(inData[i]&0xfc)>>2];
                    outChars[j+1] = base64[(inData[i]&0x03)<<4];
                    outChars[j+2] = base64[64]; //Pad
                    outChars[j+3] = base64[64]; //Pad
                    j+=4;
                    break;
                }
            }
            
            return j;
        }

        private static int ToBase64_CalculateAndValidateOutputLength(int inputLength, bool insertLineBreaks) {
            long outlen = ((long)inputLength) / 3 * 4;          // the base length - we want integer division here. 
            outlen += ((inputLength % 3) != 0) ? 4 : 0;         // at most 4 more chars for the remainder

            if (outlen == 0)
                return 0;

            if (insertLineBreaks) {
                long newLines = outlen / base64LineBreakPosition;
                if ((outlen % base64LineBreakPosition) == 0) {
                    --newLines;    
                }
                outlen += newLines * 2;              // the number of line break chars we'll add, "\r\n"
            }

            // If we overflow an int then we cannot allocate enough
            // memory to output the value so throw
            if (outlen > int.MaxValue)
                throw new OutOfMemoryException();

            return (int)outlen;
        }
        

        /// <summary>
        /// Converts the specified string, which encodes binary data as Base64 digits, to the equivalent byte array.
        /// </summary>
        /// <param name="s">The string to convert</param>
        /// <returns>The array of bytes represented by the specifed Base64 string.</returns>
        [SecuritySafeCritical] 
        public static Byte[] FromBase64String(String s) {

            // "s" is an unfortunate parameter name, but we need to keep it for backward compat.

            if (s == null)
                throw new ArgumentNullException("s");

            Contract.EndContractBlock();

            unsafe {
                fixed (Char* sPtr = s) {

                    return FromBase64CharPtr(sPtr, s.Length);
                }
            }
        }


        /// <summary>
        /// Converts the specified range of a Char array, which encodes binary data as Base64 digits, to the equivalent byte array.     
        /// </summary>
        /// <param name="inArray">Chars representing Base64 encoding characters</param>
        /// <param name="offset">A position within the input array.</param>
        /// <param name="length">Number of element to convert.</param>
        /// <returns>The array of bytes represented by the specified Base64 encoding characters.</returns>
        [SecuritySafeCritical]
        public static Byte[] FromBase64CharArray(Char[] inArray, Int32 offset, Int32 length) {

            if (inArray == null)
                throw new ArgumentNullException("inArray");

            if (length < 0)
                throw new ArgumentOutOfRangeException("length", Environment.GetResourceString("ArgumentOutOfRange_Index"));

            if (offset < 0)
                throw new ArgumentOutOfRangeException("offset", Environment.GetResourceString("ArgumentOutOfRange_GenericPositive"));

            if (offset > inArray.Length - length)
                throw new ArgumentOutOfRangeException("offset", Environment.GetResourceString("ArgumentOutOfRange_OffsetLength"));

            Contract.EndContractBlock();

            unsafe {
                fixed (Char* inArrayPtr = inArray) {

                    return FromBase64CharPtr(inArrayPtr + offset, length);
                }
            }
        }            



        /// <summary>
        /// Convert Base64 encoding characters to bytes:
        ///  - Compute result length exactly by actually walking the input;
        ///  - Allocate new result array based on computation;
        ///  - Decode input into the new array;
        /// </summary>
        /// <param name="inputPtr">Pointer to the first input char</param>
        /// <param name="inputLength">Number of input chars</param>
        /// <returns></returns>
        [SecurityCritical] 
        private static unsafe Byte[] FromBase64CharPtr(Char* inputPtr, Int32 inputLength) {

            // The validity of parameters much be checked by callers, thus we are Critical here.

            Contract.Assert(0 <= inputLength);

            // We need to get rid of any trailing white spaces.
            // Otherwise we would be rejecting input such as "abc= ":
            while (inputLength > 0)
            {
                 Int32 lastChar = inputPtr[inputLength - 1];
                 if (lastChar != (Int32) ' ' && lastChar != (Int32) '\n' && lastChar != (Int32) '\r' && lastChar != (Int32) '\t')
                       break;
                inputLength--;
            }

            // Compute the output length:
            Int32 resultLength = FromBase64_ComputeResultLength(inputPtr, inputLength);

            Contract.Assert(0 <= resultLength);

            // resultLength can be zero. We will still enter FromBase64_Decode and process the input.
            // It may either simply write no bytes (e.g. input = " ") or throw (e.g. input = "ab").
            
            // Create result byte blob:
            Byte[] decodedBytes = new Byte[resultLength];

            // Convert Base64 chars into bytes:
            Int32 actualResultLength;
            fixed (Byte* decodedBytesPtr = decodedBytes)
                actualResultLength = FromBase64_Decode(inputPtr, inputLength, decodedBytesPtr, resultLength);

            // Note that actualResultLength can differ from resultLength if the caller is modifying the array
            // as it is being converted. Silently ignore the failure.
            // Consider throwing exception in an non in-place release.

            // We are done:
            return decodedBytes;
        }


        /// <summary>
        /// Decode characters representing a Base64 encoding into bytes:
        /// Walk the input. Every time 4 chars are read, convert them to the 3 corresponding output bytes.
        /// This method is a bit lengthy on purpose. We are trying to avoid jumps to helpers in the loop
        /// to aid performance.
        /// </summary>
        /// <param name="inputPtr">Pointer to first input char</param>
        /// <param name="inputLength">Number of input chars</param>
        /// <param name="destPtr">Pointer to location for the first result byte</param>
        /// <param name="destLength">Max length of the preallocated result buffer</param>
        /// <returns>If the result buffer was not large enough to write all result bytes, return -1;
        /// Otherwise return the number of result bytes actually produced.</returns>
        [SecurityCritical]
        private static unsafe Int32 FromBase64_Decode(Char* startInputPtr, Int32 inputLength, Byte* startDestPtr, Int32 destLength) {

            // You may find this method weird to look at. It’s written for performance, not aesthetics.
            // You will find unrolled loops label jumps and bit manipulations.

            const UInt32 intA =     (UInt32) 'A';            
            const UInt32 inta =     (UInt32) 'a';            
            const UInt32 int0 =     (UInt32) '0';         
            const UInt32 intEq =    (UInt32) '=';
            const UInt32 intPlus =  (UInt32) '+';
            const UInt32 intSlash = (UInt32) '/';
            const UInt32 intSpace = (UInt32) ' ';
            const UInt32 intTab =   (UInt32) '\t';
            const UInt32 intNLn =   (UInt32) '\n';
            const UInt32 intCRt =   (UInt32) '\r';
            const UInt32 intAtoZ =  (UInt32) ('Z' - 'A');  // = ('z' - 'a')
            const UInt32 int0to9 =  (UInt32) ('9' - '0');

            Char* inputPtr = startInputPtr;
            Byte* destPtr = startDestPtr;

            // Pointers to the end of input and output:
            Char* endInputPtr = inputPtr + inputLength;
            Byte* endDestPtr = destPtr + destLength;

            // Current char code/value:
            UInt32 currCode;
             
            // This 4-byte integer will contain the 4 codes of the current 4-char group.
            // Eeach char codes for 6 bits = 24 bits.
            // The remaining byte will be FF, we use it as a marker when 4 chars have been processed.            
            UInt32 currBlockCodes = 0x000000FFu;
                            
            unchecked { while (true) {

                // break when done:
                if (inputPtr >= endInputPtr)
                    goto _AllInputConsumed;

                // Get current char:
                currCode = (UInt32) (*inputPtr);
                inputPtr++;

                // Determine current char code:

                if (currCode - intA <= intAtoZ)
                    currCode -= intA;                

                else if (currCode - inta <= intAtoZ)
                    currCode -= (inta - 26u);                

                else if (currCode - int0 <= int0to9)
                    currCode -= (int0 - 52u);

                else {
                    // Use the slower switch for less common cases:
                    switch(currCode) {

                        // Significant chars:
                        case intPlus:  currCode = 62u;
                            break;

                        case intSlash: currCode = 63u;
                            break;

                        // Legal no-value chars (we ignore these):
                        case intCRt:  case intNLn:  case intSpace:  case intTab:                             
                            continue;

                        // The equality char is only legal at the end of the input.
                        // Jump after the loop to make it easier for the JIT register predictor to do a good job for the loop itself:
                        case intEq:
                            goto _EqualityCharEncountered; 

                        // Other chars are illegal:
                        default:
                            throw new FormatException(Environment.GetResourceString("Format_BadBase64Char"));
                    }
                }

                // Ok, we got the code. Save it:
                currBlockCodes = (currBlockCodes << 6) | currCode;

                // Last bit in currBlockCodes will be on after in shifted right 4 times:
                if ((currBlockCodes & 0x80000000u) != 0u) {

                    if ((Int32) (endDestPtr - destPtr) < 3)
                         return -1;

                    *(destPtr)     = (Byte) (currBlockCodes >> 16);
                    *(destPtr + 1) = (Byte) (currBlockCodes >> 8);
                    *(destPtr + 2) = (Byte) (currBlockCodes);
                    destPtr += 3;

                    currBlockCodes = 0x000000FFu;
                }

            }}  // unchecked while

            // 'd be nice to have an assert that we never get here, but CS0162: Unreachable code detected.
            // Contract.Assert(false, "We only leave the above loop by jumping; should never get here.");

            // We jump here out of the loop if we hit an '=':
            _EqualityCharEncountered:

            Contract.Assert(currCode == intEq);

            // Recall that inputPtr is now one position past where '=' was read.
            // '=' can only be at the last input pos:
            if (inputPtr == endInputPtr) {

                // Code is zero for trailing '=':
                currBlockCodes <<= 6;

                // The '=' did not complete a 4-group. The input must be bad:
                if ((currBlockCodes & 0x80000000u) == 0u)
                    throw new FormatException(Environment.GetResourceString("Format_BadBase64CharArrayLength"));

                if ((int)(endDestPtr - destPtr) < 2)  // Autch! We underestimated the output length!
                    return -1;

                // We are good, store bytes form this past group. We had a single "=", so we take two bytes:
                *(destPtr++) = (Byte) (currBlockCodes >> 16);
                *(destPtr++) = (Byte) (currBlockCodes >> 8);

                currBlockCodes = 0x000000FFu;                

            } else { // '=' can also be at the pre-last position iff the last is also a '=' excluding the white spaces:
				
                // We need to get rid of any intermediate white spaces.
                // Otherwise we would be rejecting input such as "abc= =":
                while (inputPtr < (endInputPtr - 1))
                {
                     Int32 lastChar = *(inputPtr);
                     if (lastChar != (Int32) ' ' && lastChar != (Int32) '\n' && lastChar != (Int32) '\r' && lastChar != (Int32) '\t')
                           break;
                    inputPtr++;
                }

                if (inputPtr == (endInputPtr - 1) && *(inputPtr) == '=') {
                
                    // Code is zero for each of the two '=':
                    currBlockCodes <<= 12;

                    // The '=' did not complete a 4-group. The input must be bad:
                    if ((currBlockCodes & 0x80000000u) == 0u)
                        throw new FormatException(Environment.GetResourceString("Format_BadBase64CharArrayLength"));

                    if ((Int32) (endDestPtr - destPtr) < 1)  // Autch! We underestimated the output length!
                        return -1;

                    // We are good, store bytes form this past group. We had a "==", so we take only one byte:
                    *(destPtr++) = (Byte) (currBlockCodes >> 16);

                    currBlockCodes = 0x000000FFu;
                    
                } else  // '=' is not ok at places other than the end:
                    throw new FormatException(Environment.GetResourceString("Format_BadBase64Char"));
                            
            }
            
            // We get here either from above or by jumping out of the loop:
            _AllInputConsumed:

            // The last block of chars has less than 4 items
            if (currBlockCodes != 0x000000FFu)
                throw new FormatException(Environment.GetResourceString("Format_BadBase64CharArrayLength"));

            // Return how many bytes were actually recovered:
            return (Int32) (destPtr - startDestPtr);

        } // Int32 FromBase64_Decode(...)


        /// <summary>
        /// Compute the number of bytes encoded in the specified Base 64 char array:
        /// Walk the entire input counting white spaces and padding chars, then compute result length
        /// based on 3 bytes per 4 chars.
        /// </summary>
        [SecurityCritical]
        private static unsafe Int32 FromBase64_ComputeResultLength(Char* inputPtr, Int32 inputLength) {

            const UInt32 intEq =    (UInt32) '=';            
            const UInt32 intSpace = (UInt32) ' ';

            Contract.Assert(0 <= inputLength);

            Char* inputEndPtr = inputPtr + inputLength;
            Int32 usefulInputLength = inputLength;
            Int32 padding = 0;

            while (inputPtr < inputEndPtr) {

                UInt32 c = (UInt32) (*inputPtr);
                inputPtr++;

                // We want to be as fast as possible and filter out spaces with as few comparisons as possible.
                // We end up accepting a number of illegal chars as legal white-space chars.
                // This is ok: as soon as we hit them during actual decode we will recognise them as illegal and throw.
                if (c <= intSpace)
                    usefulInputLength--;

                else if (c == intEq) {
                    usefulInputLength--;
                    padding++;
                }
            }

            Contract.Assert(0 <= usefulInputLength);
            
            // For legal input, we can assume that 0 <= padding < 3. But it may be more for illegal input.
            // We will notice it at decode when we see a '=' at the wrong place.
            Contract.Assert(0 <= padding);

            // Perf: reuse the variable that stored the number of '=' to store the number of bytes encoded by the
            // last group that contains the '=':
            if (padding != 0) {

                if (padding == 1)
                    padding = 2;
                else if (padding == 2)
                    padding = 1;
                else
                    throw new FormatException(Environment.GetResourceString("Format_BadBase64Char"));  
            }

            // Done:
            return (usefulInputLength / 4) * 3 + padding;
        }

    }  // class Convert
}  // namespace