diff options
| author | Anas Nashif <anas.nashif@intel.com> | 2012-10-30 12:57:26 -0700 |
|---|---|---|
| committer | Anas Nashif <anas.nashif@intel.com> | 2012-10-30 12:57:26 -0700 |
| commit | 1a78a62555be32868418fe52f8e330c9d0f95d5a (patch) | |
| tree | d3765a80e7d3b9640ec2e930743630cd6b9fce2b /doc/html/boost_lexical_cast.html | |
| download | boost-1a78a62555be32868418fe52f8e330c9d0f95d5a.tar.gz boost-1a78a62555be32868418fe52f8e330c9d0f95d5a.tar.bz2 boost-1a78a62555be32868418fe52f8e330c9d0f95d5a.zip | |
Imported Upstream version 1.49.0upstream/1.49.0
Diffstat (limited to 'doc/html/boost_lexical_cast.html')
| -rw-r--r-- | doc/html/boost_lexical_cast.html | 148 |
1 files changed, 148 insertions, 0 deletions
diff --git a/doc/html/boost_lexical_cast.html b/doc/html/boost_lexical_cast.html new file mode 100644 index 0000000000..eabdd130af --- /dev/null +++ b/doc/html/boost_lexical_cast.html @@ -0,0 +1,148 @@ +<html> +<head> +<meta http-equiv="Content-Type" content="text/html; charset=US-ASCII"> +<title>Chapter 15. Boost.Lexical_Cast 1.0</title> +<link rel="stylesheet" href="../../doc/src/boostbook.css" type="text/css"> +<meta name="generator" content="DocBook XSL Stylesheets V1.76.1"> +<link rel="home" href="index.html" title="The Boost C++ Libraries BoostBook Documentation Subset"> +<link rel="up" href="libraries.html" title="Part I. The Boost C++ Libraries (BoostBook Subset)"> +<link rel="prev" href="lambda/s10.html" title="Rationale for some of the design decisions"> +<link rel="next" href="boost_lexical_cast/examples.html" title="Examples"> +</head> +<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> +<table cellpadding="2" width="100%"><tr> +<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../boost.png"></td> +<td align="center"><a href="../../index.html">Home</a></td> +<td align="center"><a href="../../libs/libraries.htm">Libraries</a></td> +<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> +<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> +<td align="center"><a href="../../more/index.htm">More</a></td> +</tr></table> +<hr> +<div class="spirit-nav"> +<a accesskey="p" href="lambda/s10.html"><img src="../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="libraries.html"><img src="../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="index.html"><img src="../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="boost_lexical_cast/examples.html"><img src="../../doc/src/images/next.png" alt="Next"></a> +</div> +<div class="chapter"> +<div class="titlepage"><div> +<div><h2 class="title"> +<a name="boost_lexical_cast"></a>Chapter 15. Boost.Lexical_Cast 1.0</h2></div> +<div><p class="copyright">Copyright © 2000-2005 Kevlin Henney</p></div> +<div><p class="copyright">Copyright © 2006-2010 Alexander Nasonov</p></div> +<div><p class="copyright">Copyright © 2011 Antony Polukhin</p></div> +<div><div class="legalnotice"> +<a name="boost_lexical_cast.legal"></a><p> + Distributed under the Boost Software License, Version 1.0. (See accompanying + file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>) + </p> +</div></div> +</div></div> +<div class="toc"> +<p><b>Table of Contents</b></p> +<dl> +<dt><span class="section"><a href="boost_lexical_cast.html#boost_lexical_cast.motivation">Motivation</a></span></dt> +<dt><span class="section"><a href="boost_lexical_cast/examples.html">Examples</a></span></dt> +<dt><span class="section"><a href="boost_lexical_cast/synopsis.html">Synopsis</a></span></dt> +<dd><dl> +<dt><span class="section"><a href="boost_lexical_cast/synopsis.html#boost_lexical_cast.synopsis.lexical_cast">lexical_cast</a></span></dt> +<dt><span class="section"><a href="boost_lexical_cast/synopsis.html#boost_lexical_cast.synopsis.bad_lexical_cast">bad_lexical_cast</a></span></dt> +</dl></dd> +<dt><span class="section"><a href="boost_lexical_cast/frequently_asked_questions.html">Frequently + Asked Questions</a></span></dt> +<dt><span class="section"><a href="boost_lexical_cast/changes.html">Changes</a></span></dt> +<dt><span class="section"><a href="boost_lexical_cast/performance.html">Performance</a></span></dt> +<dd><dl> +<dt><span class="section"><a href="boost_lexical_cast/performance.html#boost_lexical_cast.performance.tests_description">Tests + description</a></span></dt> +<dt><span class="section"><a href="boost_lexical_cast/performance.html#boost_lexical_cast.performance.clang_linux_2_8">clang-linux-2.8</a></span></dt> +<dt><span class="section"><a href="boost_lexical_cast/performance.html#boost_lexical_cast.performance.gcc_4_4">gcc-4.4</a></span></dt> +<dt><span class="section"><a href="boost_lexical_cast/performance.html#boost_lexical_cast.performance.gcc_4_5">gcc-4.5</a></span></dt> +<dt><span class="section"><a href="boost_lexical_cast/performance.html#boost_lexical_cast.performance.gcc_4_6">gcc-4.6</a></span></dt> +</dl></dd> +</dl> +</div> +<div class="section"> +<div class="titlepage"><div><div><h2 class="title" style="clear: both"> +<a name="boost_lexical_cast.motivation"></a><a class="link" href="boost_lexical_cast.html#boost_lexical_cast.motivation" title="Motivation">Motivation</a> +</h2></div></div></div> +<p> + Sometimes a value must be converted to a literal text form, such as an <code class="computeroutput"><span class="keyword">int</span></code> represented as a <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span></code>, + or vice-versa, when a <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">string</span></code> is interpreted as an <code class="computeroutput"><span class="keyword">int</span></code>. Such examples are common when converting + between data types internal to a program and representation external to a program, + such as windows and configuration files. + </p> +<p> + The standard C and C++ libraries offer a number of facilities for performing + such conversions. However, they vary with their ease of use, extensibility, + and safety. + </p> +<p> + For instance, there are a number of limitations with the family of standard + C functions typified by <code class="computeroutput"><span class="identifier">atoi</span></code>: + </p> +<div class="itemizedlist"><ul class="itemizedlist" type="disc"> +<li class="listitem"> + Conversion is supported in one direction only: from text to internal data + type. Converting the other way using the C library requires either the + inconvenience and compromised safety of the <code class="computeroutput"><span class="identifier">sprintf</span></code> + function, or the loss of portability associated with non-standard functions + such as <code class="computeroutput"><span class="identifier">itoa</span></code>. + </li> +<li class="listitem"> + The range of types supported is only a subset of the built-in numeric types, + namely <code class="computeroutput"><span class="keyword">int</span></code>, <code class="computeroutput"><span class="keyword">long</span></code>, and <code class="computeroutput"><span class="keyword">double</span></code>. + </li> +<li class="listitem"> + The range of types cannot be extended in a uniform manner. For instance, + conversion from string representation to complex or rational. + </li> +</ul></div> +<p> + The standard C functions typified by <code class="computeroutput"><span class="identifier">strtol</span></code> + have the same basic limitations, but offer finer control over the conversion + process. However, for the common case such control is often either not required + or not used. The <code class="computeroutput"><span class="identifier">scanf</span></code> family + of functions offer even greater control, but also lack safety and ease of use. + </p> +<p> + The standard C++ library offers <code class="computeroutput"><span class="identifier">stringstream</span></code> + for the kind of in-core formatting being discussed. It offers a great deal + of control over the formatting and conversion of I/O to and from arbitrary + types through text. However, for simple conversions direct use of <code class="computeroutput"><span class="identifier">stringstream</span></code> can be either clumsy (with the + introduction of extra local variables and the loss of infix-expression convenience) + or obscure (where <code class="computeroutput"><span class="identifier">stringstream</span></code> + objects are created as temporary objects in an expression). Facets provide + a comprehensive concept and facility for controlling textual representation, + but their perceived complexity and high entry level requires an extreme degree + of involvement for simple conversions, and excludes all but a few programmers. + </p> +<p> + The <code class="computeroutput"><span class="identifier">lexical_cast</span></code> function template + offers a convenient and consistent form for supporting common conversions to + and from arbitrary types when they are represented as text. The simplification + it offers is in expression-level convenience for such conversions. For more + involved conversions, such as where precision or formatting need tighter control + than is offered by the default behavior of <code class="computeroutput"><span class="identifier">lexical_cast</span></code>, + the conventional <code class="computeroutput"><span class="identifier">std</span><span class="special">::</span><span class="identifier">stringstream</span></code> approach is recommended. Where + the conversions are numeric to numeric, <a href="../../libs/numeric/conversion/doc/html/boost_numericconversion/improved_numeric_cast__.html" target="_top"><code class="computeroutput"><span class="identifier">boost</span><span class="special">::</span><span class="identifier">numeric_cast</span></code></a> + may offer more reasonable behavior than <code class="computeroutput"><span class="identifier">lexical_cast</span></code>. + </p> +<p> + For a good discussion of the options and issues involved in string-based formatting, + including comparison of <code class="computeroutput"><span class="identifier">stringstream</span></code>, + <code class="computeroutput"><span class="identifier">lexical_cast</span></code>, and others, see + Herb Sutter's article, <a href="http://www.gotw.ca/publications/mill19.htm" target="_top">The + String Formatters of Manor Farm</a>. Also, take a look at the <a class="link" href="boost_lexical_cast/performance.html" title="Performance">Performance</a> + section. + </p> +</div> +</div> +<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> +<td align="left"><p><small>Last revised: February 20, 2012 at 20:49:22 GMT</small></p></td> +<td align="right"><div class="copyright-footer"></div></td> +</tr></table> +<hr> +<div class="spirit-nav"> +<a accesskey="p" href="lambda/s10.html"><img src="../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="libraries.html"><img src="../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="index.html"><img src="../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="boost_lexical_cast/examples.html"><img src="../../doc/src/images/next.png" alt="Next"></a> +</div> +</body> +</html> |