139 lines
12 KiB
HTML
139 lines
12 KiB
HTML
<!DOCTYPE html>
|
|
<html lang="zh" dir="ltr" class="client-nojs" xmlns="http://www.w3.org/1999/xhtml" xml:lang="zh">
|
|
<head><meta http-equiv="x-ua-compatible" content="ie=edge">
|
|
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
|
|
<title>std::toupper</title>
|
|
<link rel="stylesheet" href="ext.css" />
|
|
<link rel="stylesheet" href="site_modules.css" />
|
|
</head>
|
|
<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_string_byte_toupper skin-cppreference2 action-view cpp-navbar">
|
|
<div id="cpp-content-base">
|
|
<div id="content"><a id="top"></a>
|
|
<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::</span>toupper</h1>
|
|
<div id="bodyContent">
|
|
<div id="contentSub"><span class="subpages">< <a href="cpp.html">cpp</a>‎ | <a href="cpp-string.html">string</a>‎ | <a href="cpp-string-byte.html">byte</a></span></div>
|
|
<div id="mw-content-text" lang="zh" dir="ltr" class="mw-content-ltr" xml:lang="zh">
|
|
<table class="t-dcl-begin">
|
|
<tbody>
|
|
<tr class="t-dsc-header">
|
|
<td>
|
|
<div>定义于头文件 <code><a href="cpp-header-cctype.html"><cctype></a></code></div>
|
|
</td>
|
|
<td></td>
|
|
<td></td>
|
|
</tr>
|
|
<tr class="t-dcl">
|
|
<td class="t-dcl-nopad">
|
|
<div><span class="mw-geshi cpp source-cpp"><span class="kw4">int</span> toupper<span class="br0">(</span> <span class="kw4">int</span> ch <span class="br0">)</span><span class="sy4">;</span></span></div>
|
|
</td>
|
|
<td class="t-dcl-nopad"></td>
|
|
<td class="t-dcl-nopad"></td>
|
|
</tr>
|
|
<tr class="t-dcl-sep">
|
|
<td></td>
|
|
<td></td>
|
|
<td></td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
<p>按照当前安装的 C 本地环境所定义的字符转换规则，转换给定字符为大写。</p>
|
|
<p>默认 "C" 本地环境中，分别以大写字母 <code>ABCDEFGHIJKLMNOPQRSTUVWXYZ</code> 替换下列小写字母 <code>abcdefghijklmnopqrstuvwxyz</code> 。</p>
|
|
<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">参数</span></h3>
|
|
<table class="t-par-begin">
|
|
<tr class="t-par">
|
|
<td>ch</td>
|
|
<td>-</td>
|
|
<td>要转化的字符。若 <code>ch</code> 的值不能表示为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">unsigned</span> <span class="kw4">char</span></span></span> 且不等于 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-io-c.html"><span class="kw1882">EOF</span></a></span></span> ，则行为未定义。</td>
|
|
</tr>
|
|
</table>
|
|
<h3><span class="mw-headline" id=".E8.BF.94.E5.9B.9E.E5.80.BC">返回值</span></h3>
|
|
<p>被转换的字符，或若当前 C 本地环境不定义大写版本则为 <code>ch</code> 。</p>
|
|
<h3><span class="mw-headline" id=".E6.B3.A8.E6.84.8F">注意</span></h3>
|
|
<p>同所有其他来自 <a href="cpp-header-cctype.html"><tt><cctype></tt></a> 的函数，若参数值既不能表示为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">unsigned</span> <span class="kw4">char</span></span></span> 又不等于 <code>EOF</code> 则 <code>std::toupper</code> 的行为未定义。为了以简单的 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">char</span></span></span> （或 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">signed</span> <span class="kw4">char</span></span></span> ）安全使用此函数，首先要将参数转换为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">unsigned</span> <span class="kw4">char</span></span></span> ：</p>
|
|
<div dir="ltr" class="mw-geshi" style="text-align: left;">
|
|
<div class="cpp source-cpp">
|
|
<pre class="de1"><span class="kw4">char</span> my_toupper<span class="br0">(</span><span class="kw4">char</span> ch<span class="br0">)</span>
|
|
<span class="br0">{</span>
|
|
<span class="kw1">return</span> <span class="kw1">static_cast</span><span class="sy1"><</span><span class="kw4">char</span><span class="sy1">></span><span class="br0">(</span>std<span class="sy4">::</span><span class="me2">toupper</span><span class="br0">(</span><span class="kw1">static_cast</span><span class="sy1"><</span><span class="kw4">unsigned</span> <span class="kw4">char</span><span class="sy1">></span><span class="br0">(</span>ch<span class="br0">)</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
|
|
<span class="br0">}</span></pre></div>
|
|
</div>
|
|
<p>类似地，迭代器的值类型为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">char</span></span></span> 或 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">signed</span> <span class="kw4">char</span></span></span> 时，不应直接将它们用于标准算法。而是要首先转换值为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">unsigned</span> <span class="kw4">char</span></span></span> ：</p>
|
|
<div dir="ltr" class="mw-geshi" style="text-align: left;">
|
|
<div class="cpp source-cpp">
|
|
<pre class="de1"><a href="cpp-string-basic_string.html"><span class="kw1230">std::<span class="me2">string</span></span></a> str_toupper<span class="br0">(</span><a href="cpp-string-basic_string.html"><span class="kw1230">std::<span class="me2">string</span></span></a> s<span class="br0">)</span> <span class="br0">{</span>
|
|
<a href="cpp-algorithm-transform.html"><span class="kw1589">std::<span class="me2">transform</span></span></a><span class="br0">(</span>s.<span class="me1">begin</span><span class="br0">(</span><span class="br0">)</span>, s.<span class="me1">end</span><span class="br0">(</span><span class="br0">)</span>, s.<span class="me1">begin</span><span class="br0">(</span><span class="br0">)</span>,
|
|
<span class="co1">// static_cast<int(*)(int)>(std::toupper) // 错误</span>
|
|
<span class="co1">// [](int c){ return std::toupper(c); } // 错误</span>
|
|
<span class="co1">// [](char c){ return std::toupper(c); } // 错误</span>
|
|
<span class="br0">[</span><span class="br0">]</span><span class="br0">(</span><span class="kw4">unsigned</span> <span class="kw4">char</span> c<span class="br0">)</span><span class="br0">{</span> <span class="kw1">return</span> std<span class="sy4">::</span><span class="me2">toupper</span><span class="br0">(</span>c<span class="br0">)</span><span class="sy4">;</span> <span class="br0">}</span> <span class="co1">// 正确</span>
|
|
<span class="br0">)</span><span class="sy4">;</span>
|
|
<span class="kw1">return</span> s<span class="sy4">;</span>
|
|
<span class="br0">}</span></pre></div>
|
|
</div>
|
|
<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">示例</span></h3>
|
|
<div class="t-example">
|
|
<div class="t-example-live-link"></div>
|
|
<div dir="ltr" class="mw-geshi" style="text-align: left;">
|
|
<div class="cpp source-cpp">
|
|
<pre class="de1"><span class="co2">#include <iostream></span>
|
|
<span class="co2">#include <cctype></span>
|
|
<span class="co2">#include <clocale></span>
|
|
|
|
<span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
|
|
<span class="br0">{</span>
|
|
<span class="kw4">unsigned</span> <span class="kw4">char</span> c <span class="sy1">=</span> <span class="st0">'<span class="es2">\xb8</span>'</span><span class="sy4">;</span> <span class="co1">// ISO-8859-15 中的字符 ž</span>
|
|
<span class="co1">// 但在 ISO-8859-1 中为 ¸ （下加符）</span>
|
|
|
|
<a href="cpp-locale-setlocale.html"><span class="kw1990">std::<span class="me2">setlocale</span></span></a><span class="br0">(</span><a href="cpp-locale-LC_categories.html"><span class="kw1993">LC_ALL</span></a>, <span class="st0">"en_US.iso88591"</span><span class="br0">)</span><span class="sy4">;</span>
|
|
<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <a href="cpp-io-manip-hex.html"><span class="kw1782">std::<span class="me2">hex</span></span></a> <span class="sy1"><<</span> <a href="cpp-io-manip-showbase.html"><span class="kw1766">std::<span class="me2">showbase</span></span></a><span class="sy4">;</span>
|
|
<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">"in iso8859-1, toupper('0xb8') gives "</span> <span class="sy1"><<</span> std<span class="sy4">::</span><span class="me2">toupper</span><span class="br0">(</span>c<span class="br0">)</span> <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span><span class="sy4">;</span>
|
|
<a href="cpp-locale-setlocale.html"><span class="kw1990">std::<span class="me2">setlocale</span></span></a><span class="br0">(</span><a href="cpp-locale-LC_categories.html"><span class="kw1993">LC_ALL</span></a>, <span class="st0">"en_US.iso885915"</span><span class="br0">)</span><span class="sy4">;</span>
|
|
<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">"in iso8859-15, toupper('0xb8') gives "</span> <span class="sy1"><<</span> std<span class="sy4">::</span><span class="me2">toupper</span><span class="br0">(</span>c<span class="br0">)</span> <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span><span class="sy4">;</span>
|
|
<span class="br0">}</span></pre></div>
|
|
</div>
|
|
<p>输出：</p>
|
|
<div dir="ltr" class="mw-geshi" style="text-align: left;">
|
|
<div class="text source-text">
|
|
<pre class="de1">in iso8859-1, toupper('0xb8') gives 0xb8
|
|
in iso8859-15, toupper('0xb8') gives 0xb4</pre></div>
|
|
</div>
|
|
</div>
|
|
<p><br /></p>
|
|
<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">参阅</span></h3>
|
|
<table class="t-dsc-begin">
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="cpp-string-byte-tolower.html"><span class="t-lines"><span>tolower</span></span></a></div>
|
|
</div>
|
|
</td>
|
|
<td>转换字符为小写<br />
|
|
<span class="t-mark">(函数)</span></td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="cpp-locale-toupper.html"><span class="t-lines"><span>toupper<span class="t-dsc-small">(std::locale)</span></span></span></a></div>
|
|
</div>
|
|
</td>
|
|
<td>用本地环境的 ctype 刻面将字符转换为大写<br />
|
|
<span class="t-mark">(函数模板)</span></td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="cpp-string-wide-towupper.html"><span class="t-lines"><span>towupper</span></span></a></div>
|
|
</div>
|
|
</td>
|
|
<td>转换宽字符为大写<br />
|
|
<span class="t-mark">(函数)</span></td>
|
|
</tr>
|
|
</table>
|
|
</div>
|
|
<div class="visualClear"></div>
|
|
</div>
|
|
</div>
|
|
</div>
|
|
</body>
|
|
</html>
|