// 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. using System; using System.Diagnostics.Contracts; namespace System.Collections { // An IList is an ordered collection of objects. The exact ordering // is up to the implementation of the list, ranging from a sorted // order to insertion order. public interface IList : ICollection { // The Item property provides methods to read and edit entries in the List. Object this[int index] { get; set; } // Adds an item to the list. The exact position in the list is // implementation-dependent, so while ArrayList may always insert // in the last available location, a SortedList most likely would not. // The return value is the position the new element was inserted in. int Add(Object value); // Returns whether the list contains a particular item. bool Contains(Object value); // Removes all items from the list. void Clear(); bool IsReadOnly { get; } bool IsFixedSize { get; } // Returns the index of a particular item, if it is in the list. // Returns -1 if the item isn't in the list. int IndexOf(Object value); // Inserts value into the list at position index. // index must be non-negative and less than or equal to the // number of elements in the list. If index equals the number // of items in the list, then value is appended to the end. void Insert(int index, Object value); // Removes an item from the list. void Remove(Object value); // Removes the item at position index. void RemoveAt(int index); } }