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diff --git a/gcc-4.4.3/libstdc++-v3/doc/html/manual/bk01pt05ch13.html b/gcc-4.4.3/libstdc++-v3/doc/html/manual/bk01pt05ch13.html new file mode 100644 index 000000000..07535c3c5 --- /dev/null +++ b/gcc-4.4.3/libstdc++-v3/doc/html/manual/bk01pt05ch13.html @@ -0,0 +1,95 @@ +<?xml version="1.0" encoding="UTF-8" standalone="no"?> +<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> +<html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>Chapter 13. String Classes</title><meta name="generator" content="DocBook XSL Stylesheets V1.74.0" /><meta name="keywords" content=" ISO C++ , library " /><link rel="home" href="../spine.html" title="The GNU C++ Library Documentation" /><link rel="up" href="strings.html" title="Part V. Strings" /><link rel="prev" href="strings.html" title="Part V. Strings" /><link rel="next" href="bk01pt05ch13s02.html" title="Case Sensitivity" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Chapter 13. String Classes</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="strings.html">Prev</a> </td><th width="60%" align="center">Part V. + Strings + +</th><td width="20%" align="right"> <a accesskey="n" href="bk01pt05ch13s02.html">Next</a></td></tr></table><hr /></div><div class="chapter" lang="en" xml:lang="en"><div class="titlepage"><div><div><h2 class="title"><a id="manual.strings.string"></a>Chapter 13. String Classes</h2></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="sect1"><a href="bk01pt05ch13.html#strings.string.simple">Simple Transformations</a></span></dt><dt><span class="sect1"><a href="bk01pt05ch13s02.html">Case Sensitivity</a></span></dt><dt><span class="sect1"><a href="bk01pt05ch13s03.html">Arbitrary Character Types</a></span></dt><dt><span class="sect1"><a href="bk01pt05ch13s04.html">Tokenizing</a></span></dt><dt><span class="sect1"><a href="bk01pt05ch13s05.html">Shrink to Fit</a></span></dt><dt><span class="sect1"><a href="bk01pt05ch13s06.html">CString (MFC)</a></span></dt></dl></div><div class="sect1" lang="en" xml:lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="strings.string.simple"></a>Simple Transformations</h2></div></div></div><p> + Here are Standard, simple, and portable ways to perform common + transformations on a <code class="code">string</code> instance, such as + "convert to all upper case." The word transformations + is especially apt, because the standard template function + <code class="code">transform<></code> is used. + </p><p> + This code will go through some iterations. Here's a simple + version: + </p><pre class="programlisting"> + #include <string> + #include <algorithm> + #include <cctype> // old <ctype.h> + + struct ToLower + { + char operator() (char c) const { return std::tolower(c); } + }; + + struct ToUpper + { + char operator() (char c) const { return std::toupper(c); } + }; + + int main() + { + std::string s ("Some Kind Of Initial Input Goes Here"); + + // Change everything into upper case + std::transform (s.begin(), s.end(), s.begin(), ToUpper()); + + // Change everything into lower case + std::transform (s.begin(), s.end(), s.begin(), ToLower()); + + // Change everything back into upper case, but store the + // result in a different string + std::string capital_s; + capital_s.resize(s.size()); + std::transform (s.begin(), s.end(), capital_s.begin(), ToUpper()); + } + </pre><p> + <span class="emphasis"><em>Note</em></span> that these calls all + involve the global C locale through the use of the C functions + <code class="code">toupper/tolower</code>. This is absolutely guaranteed to work -- + but <span class="emphasis"><em>only</em></span> if the string contains <span class="emphasis"><em>only</em></span> characters + from the basic source character set, and there are <span class="emphasis"><em>only</em></span> + 96 of those. Which means that not even all English text can be + represented (certain British spellings, proper names, and so forth). + So, if all your input forevermore consists of only those 96 + characters (hahahahahaha), then you're done. + </p><p><span class="emphasis"><em>Note</em></span> that the + <code class="code">ToUpper</code> and <code class="code">ToLower</code> function objects + are needed because <code class="code">toupper</code> and <code class="code">tolower</code> + are overloaded names (declared in <code class="code"><cctype></code> and + <code class="code"><locale></code>) so the template-arguments for + <code class="code">transform<></code> cannot be deduced, as explained in + <a class="ulink" href="http://gcc.gnu.org/ml/libstdc++/2002-11/msg00180.html" target="_top">this + message</a>. + + At minimum, you can write short wrappers like + </p><pre class="programlisting"> + char toLower (char c) + { + return std::tolower(c); + } </pre><p>The correct method is to use a facet for a particular locale + and call its conversion functions. These are discussed more in + Chapter 22; the specific part is + <a class="ulink" href="../22_locale/howto.html#7" target="_top">Correct Transformations</a>, + which shows the final version of this code. (Thanks to James Kanze + for assistance and suggestions on all of this.) + </p><p>Another common operation is trimming off excess whitespace. Much + like transformations, this task is trivial with the use of string's + <code class="code">find</code> family. These examples are broken into multiple + statements for readability: + </p><pre class="programlisting"> + std::string str (" \t blah blah blah \n "); + + // trim leading whitespace + string::size_type notwhite = str.find_first_not_of(" \t\n"); + str.erase(0,notwhite); + + // trim trailing whitespace + notwhite = str.find_last_not_of(" \t\n"); + str.erase(notwhite+1); </pre><p>Obviously, the calls to <code class="code">find</code> could be inserted directly + into the calls to <code class="code">erase</code>, in case your compiler does not + optimize named temporaries out of existence. + </p></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="strings.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="strings.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="bk01pt05ch13s02.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Part V. + Strings + + </td><td width="20%" align="center"><a accesskey="h" href="../spine.html">Home</a></td><td width="40%" align="right" valign="top"> Case Sensitivity</td></tr></table></div></body></html> |