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<!DOCTYPE html>
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<html lang="zh" dir="ltr" class="client-nojs" xmlns="http://www.w3.org/1999/xhtml" xml:lang="zh">
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<head><meta http-equiv="x-ua-compatible" content="ie=edge">
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<title>std::stoi, std::stol, std::stoll</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_string_basic_string_stol skin-cppreference2 action-view cpp-navbar">
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::</span>stoi, <span style="font-size:0.7em; line-height:130%">std::</span>stol, <span style="font-size:0.7em; line-height:130%">std::</span>stoll</h1>
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<div id="bodyContent">
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<div id="contentSub"><span class="subpages">< <a href="cpp.html">cpp</a>‎ | <a href="cpp-string.html">string</a>‎ | <a href="cpp-string-basic_string.html">basic string</a></span></div>
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<div id="mw-content-text" lang="zh" dir="ltr" class="mw-content-ltr" xml:lang="zh">
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<table class="t-dcl-begin">
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<tbody>
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<tr class="t-dsc-header">
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<td>
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<div>定义于头文件 <code><a href="cpp-header-string.html"><string></a></code></div>
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</td>
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<td></td>
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<td></td>
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</tr>
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<tr class="t-dcl t-since-cxx11">
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<td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">int</span> stoi<span class="br0">(</span> <span class="kw4">const</span> <a href="cpp-string-basic_string.html"><span class="kw1230">std::<span class="me2">string</span></span></a><span class="sy3">&</span> str, <a href="cpp-types-size_t.html"><span class="kw100">std::<span class="me2">size_t</span></span></a><span class="sy2">*</span> pos <span class="sy1">=</span> <span class="nu0">0</span>, <span class="kw4">int</span> base <span class="sy1">=</span> <span class="nu0">10</span> <span class="br0">)</span><span class="sy4">;</span><br />
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<span class="kw4">int</span> stoi<span class="br0">(</span> <span class="kw4">const</span> <a href="cpp-string-basic_string.html"><span class="kw1232">std::<span class="me2">wstring</span></span></a><span class="sy3">&</span> str, <a href="cpp-types-size_t.html"><span class="kw100">std::<span class="me2">size_t</span></span></a><span class="sy2">*</span> pos <span class="sy1">=</span> <span class="nu0">0</span>, <span class="kw4">int</span> base <span class="sy1">=</span> <span class="nu0">10</span> <span class="br0">)</span><span class="sy4">;</span></span></div>
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</td>
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<td>(1)</td>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span></td>
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</tr>
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<tr class="t-dcl t-since-cxx11">
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<td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">long</span> stol<span class="br0">(</span> <span class="kw4">const</span> <a href="cpp-string-basic_string.html"><span class="kw1230">std::<span class="me2">string</span></span></a><span class="sy3">&</span> str, <a href="cpp-types-size_t.html"><span class="kw100">std::<span class="me2">size_t</span></span></a><span class="sy2">*</span> pos <span class="sy1">=</span> <span class="nu0">0</span>, <span class="kw4">int</span> base <span class="sy1">=</span> <span class="nu0">10</span> <span class="br0">)</span><span class="sy4">;</span><br />
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<span class="kw4">long</span> stol<span class="br0">(</span> <span class="kw4">const</span> <a href="cpp-string-basic_string.html"><span class="kw1232">std::<span class="me2">wstring</span></span></a><span class="sy3">&</span> str, <a href="cpp-types-size_t.html"><span class="kw100">std::<span class="me2">size_t</span></span></a><span class="sy2">*</span> pos <span class="sy1">=</span> <span class="nu0">0</span>, <span class="kw4">int</span> base <span class="sy1">=</span> <span class="nu0">10</span> <span class="br0">)</span><span class="sy4">;</span></span></div>
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</td>
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<td>(2)</td>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span></td>
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</tr>
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<tr class="t-dcl t-since-cxx11">
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<td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">long</span> <span class="kw4">long</span> stoll<span class="br0">(</span> <span class="kw4">const</span> <a href="cpp-string-basic_string.html"><span class="kw1230">std::<span class="me2">string</span></span></a><span class="sy3">&</span> str, <a href="cpp-types-size_t.html"><span class="kw100">std::<span class="me2">size_t</span></span></a><span class="sy2">*</span> pos <span class="sy1">=</span> <span class="nu0">0</span>, <span class="kw4">int</span> base <span class="sy1">=</span> <span class="nu0">10</span> <span class="br0">)</span><span class="sy4">;</span><br />
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<span class="kw4">long</span> <span class="kw4">long</span> stoll<span class="br0">(</span> <span class="kw4">const</span> <a href="cpp-string-basic_string.html"><span class="kw1232">std::<span class="me2">wstring</span></span></a><span class="sy3">&</span> str, <a href="cpp-types-size_t.html"><span class="kw100">std::<span class="me2">size_t</span></span></a><span class="sy2">*</span> pos <span class="sy1">=</span> <span class="nu0">0</span>, <span class="kw4">int</span> base <span class="sy1">=</span> <span class="nu0">10</span> <span class="br0">)</span><span class="sy4">;</span></span></div>
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</td>
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<td>(3)</td>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span></td>
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</tr>
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<tr class="t-dcl-sep">
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<td></td>
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<td></td>
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<td></td>
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</tr>
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</tbody>
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</table>
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<p>转译字符串 <code>str</code> 中的有符号整数值。</p>
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<div class="t-li1"><span class="t-li">1)</span> 调用 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-string-byte-strtol.html"><span class="kw1131">std::<span class="me2">strtol</span></span></a><span class="br0">(</span>str.<span class="me1">c_str</span><span class="br0">(</span><span class="br0">)</span>, <span class="sy3">&</span>ptr, base<span class="br0">)</span></span></span> 或 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-string-wide-wcstol.html"><span class="kw1201">std::<span class="me2">wcstol</span></span></a><span class="br0">(</span>str.<span class="me1">c_str</span><span class="br0">(</span><span class="br0">)</span>, <span class="sy3">&</span>ptr, base<span class="br0">)</span></span></span></div>
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<div class="t-li1"><span class="t-li">2)</span> 调用 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-string-byte-strtol.html"><span class="kw1131">std::<span class="me2">strtol</span></span></a><span class="br0">(</span>str.<span class="me1">c_str</span><span class="br0">(</span><span class="br0">)</span>, <span class="sy3">&</span>ptr, base<span class="br0">)</span></span></span> 或 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-string-wide-wcstol.html"><span class="kw1201">std::<span class="me2">wcstol</span></span></a><span class="br0">(</span>str.<span class="me1">c_str</span><span class="br0">(</span><span class="br0">)</span>, <span class="sy3">&</span>ptr, base<span class="br0">)</span></span></span></div>
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<div class="t-li1"><span class="t-li">3)</span> 调用 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-string-byte-strtol.html"><span class="kw1132">std::<span class="me2">strtoll</span></span></a><span class="br0">(</span>str.<span class="me1">c_str</span><span class="br0">(</span><span class="br0">)</span>, <span class="sy3">&</span>ptr, base<span class="br0">)</span></span></span> 或 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-string-wide-wcstol.html"><span class="kw1202">std::<span class="me2">wcstoll</span></span></a><span class="br0">(</span>str.<span class="me1">c_str</span><span class="br0">(</span><span class="br0">)</span>, <span class="sy3">&</span>ptr, base<span class="br0">)</span></span></span></div>
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<p>舍弃所有空白符（以调用 <code>isspace()</code> 鉴别），直到找到首个非空白符，然后取尽可能多的字符组成<i>底 n</i> （其中 n=base ）的整数表示，并将它们转换成一个整数值。合法的整数值由下列部分组成：</p>
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<ul>
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<li><span class="t-mark">(可选)</span>正或负号</li>
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<li><span class="t-mark">(可选)</span>指示八进制底的前缀（ <code><b>0</b></code> ）（仅当底为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="nu0">8</span></span></span> 或 <span class="t-c"><span class="mw-geshi cpp source-cpp">​<span class="nu0">0</span>​</span></span> 时应用）</li>
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<li><span class="t-mark">(可选)</span>指示十六进制底的前缀（ <code><b>0x</b></code> 或 <code><b>0X</b></code> ）（仅当底为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="nu0">16</span></span></span> 或 <span class="t-c"><span class="mw-geshi cpp source-cpp">​<span class="nu0">0</span>​</span></span> 时应用）</li>
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<li>一个数字序列</li>
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</ul>
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<p>底的合法集是 {0,2,3,...,36} 。合法数字集对于底 2 整数是 <code>{0,1</code>}，对于底3整数是 <code>{0,1,2</code>} ，以此类推。对于大于 <code>10</code> 的底，合法数字包含字母字符，从对于底 11 整数的 <code>Aa</code> 到对于底36整数的 <code>Zz</code> 。忽略字符大小写。</p>
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<p>当前安装的 C <a href="cpp-locale-setlocale.html">本地环境</a>可能接受另外的数字格式。</p>
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<p>若 base 为 <span class="t-c"><span class="mw-geshi cpp source-cpp">​<span class="nu0">0</span>​</span></span> ，则自动检测数值进制：若前缀为 <code><b>0</b></code> ，则底为八进制，若前缀为 <code><b>0x</b></code> 或 <code><b>0X</b></code> ，则底为十六进制，否则底为十进制。</p>
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<p>若符号是输入序列的一部分，则对从数字序列计算得来的数字值取反，如同用结果类型的<a href="cpp-language-operator_arithmetic.html#.E4.B8.80.E5.85.83.E7.AE.97.E6.9C.AF.E8.BF.90.E7.AE.97.E7.AC.A6">一元减</a>。</p>
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<p>若 <code>pos</code> 不是空指针，则指针 <code>ptr</code> ——转换函数内部者——将接收 <span class="t-c"><span class="mw-geshi cpp source-cpp">str.<span class="me1">c_str</span><span class="br0">(</span><span class="br0">)</span></span></span> 中首个未转换字符的地址，将计算该字符的下标并存储之于 <code>*pos</code> ，该对象给出转换所处理的字符数。</p>
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<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">参数</span></h3>
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<table class="t-par-begin">
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<tr class="t-par">
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<td>str</td>
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<td>-</td>
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<td>要转换的字符串</td>
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</tr>
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<tr class="t-par">
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<td>pos</td>
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<td>-</td>
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<td>存储已处理字符数的整数的地址</td>
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</tr>
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<tr class="t-par">
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<td>base</td>
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<td>-</td>
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<td>数的底</td>
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</tr>
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</table>
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<h3><span class="mw-headline" id=".E8.BF.94.E5.9B.9E.E5.80.BC">返回值</span></h3>
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<p>对应 <code>str</code> 内容的整数值。</p>
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<h3><span class="mw-headline" id=".E5.BC.82.E5.B8.B8">异常</span></h3>
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<ul>
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<li>若不能进行转换则为 <span class="t-lc"><a href="cpp-error-invalid_argument.html">std::invalid_argument</a></span></li>
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<li>若转换值会落在结果类型的范围外，或若底层函数（ std::strtol 或 std::strtoll ）设置 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">errno</span></span></span> 为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-error-errno_macros.html"><span class="kw862">ERANGE</span></a></span></span> 则为 <span class="t-lc"><a href="cpp-error-out_of_range.html">std::out_of_range</a></span> 。</li>
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</ul>
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<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">示例</span></h3>
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<div class="t-example">
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<div class="t-example-live-link"></div>
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<div dir="ltr" class="mw-geshi" style="text-align: left;">
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<div class="cpp source-cpp">
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<pre class="de1"><span class="co2">#include <iostream></span>
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<span class="co2">#include <string></span>
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<span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
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<span class="br0">{</span>
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<a href="cpp-string-basic_string.html"><span class="kw1230">std::<span class="me2">string</span></span></a> str1 <span class="sy1">=</span> <span class="st0">"45"</span><span class="sy4">;</span>
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<a href="cpp-string-basic_string.html"><span class="kw1230">std::<span class="me2">string</span></span></a> str2 <span class="sy1">=</span> <span class="st0">"3.14159"</span><span class="sy4">;</span>
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<a href="cpp-string-basic_string.html"><span class="kw1230">std::<span class="me2">string</span></span></a> str3 <span class="sy1">=</span> <span class="st0">"31337 with words"</span><span class="sy4">;</span>
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<a href="cpp-string-basic_string.html"><span class="kw1230">std::<span class="me2">string</span></span></a> str4 <span class="sy1">=</span> <span class="st0">"words and 2"</span><span class="sy4">;</span>
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<span class="kw4">int</span> myint1 <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">stoi</span><span class="br0">(</span>str1<span class="br0">)</span><span class="sy4">;</span>
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<span class="kw4">int</span> myint2 <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">stoi</span><span class="br0">(</span>str2<span class="br0">)</span><span class="sy4">;</span>
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<span class="kw4">int</span> myint3 <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">stoi</span><span class="br0">(</span>str3<span class="br0">)</span><span class="sy4">;</span>
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<span class="co1">// 错误： 'std::invalid_argument'</span>
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<span class="co1">// int myint4 = std::stoi(str4);</span>
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<a href="cpp-io-cout.html"><span class="kw1755">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">"std::stoi(<span class="es1">\"</span>"</span> <span class="sy1"><<</span> str1 <span class="sy1"><<</span> <span class="st0">"<span class="es1">\"</span>) is "</span> <span class="sy1"><<</span> myint1 <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span><span class="sy4">;</span>
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<a href="cpp-io-cout.html"><span class="kw1755">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">"std::stoi(<span class="es1">\"</span>"</span> <span class="sy1"><<</span> str2 <span class="sy1"><<</span> <span class="st0">"<span class="es1">\"</span>) is "</span> <span class="sy1"><<</span> myint2 <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span><span class="sy4">;</span>
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<a href="cpp-io-cout.html"><span class="kw1755">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">"std::stoi(<span class="es1">\"</span>"</span> <span class="sy1"><<</span> str3 <span class="sy1"><<</span> <span class="st0">"<span class="es1">\"</span>) is "</span> <span class="sy1"><<</span> myint3 <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span><span class="sy4">;</span>
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<span class="co1">//std::cout << "std::stoi(\"" << str4 << "\") is " << myint4 << '\n';</span>
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<span class="br0">}</span></pre></div>
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</div>
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<p>输出：</p>
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<div dir="ltr" class="mw-geshi" style="text-align: left;">
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<div class="text source-text">
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<pre class="de1">std::stoi("45") is 45
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std::stoi("3.14159") is 3
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std::stoi("31337 with words") is 31337</pre></div>
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</div>
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</div>
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<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">参阅</span></h3>
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<table class="t-dsc-begin">
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<tr class="t-dsc">
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<td>
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<div class="t-dsc-member-div">
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<div><a href="cpp-string-basic_string-stoul.html"><span class="t-lines"><span>stoul</span><span>stoull</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div>
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</div>
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</td>
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<td>转换字符串为无符号整数<br />
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<span class="t-mark">(函数)</span></td>
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</tr>
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<tr class="t-dsc">
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<td>
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<div class="t-dsc-member-div">
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<div><a href="cpp-string-basic_string-stof.html"><span class="t-lines"><span>stof</span><span>stod</span><span>stold</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div>
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||||
</div>
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||||
</td>
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<td>转换字符串为浮点值<br />
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<span class="t-mark">(函数)</span></td>
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</tr>
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||||
<tr class="t-dsc">
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||||
<td>
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||||
<div class="t-dsc-member-div">
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<div><a href="cpp-string-byte-strtol.html"><span class="t-lines"><span>strtol</span><span>strtoll</span></span></a></div>
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<div><span class="t-lines"><span></span><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div>
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||||
</div>
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||||
</td>
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<td>转换字节字符串为整数值<br />
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<span class="t-mark">(函数)</span></td>
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||||
</tr>
|
||||
<tr class="t-dsc">
|
||||
<td>
|
||||
<div class="t-dsc-member-div">
|
||||
<div><a href="cpp-string-byte-strtoul.html"><span class="t-lines"><span>strtoul</span><span>strtoull</span></span></a></div>
|
||||
<div><span class="t-lines"><span></span><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div>
|
||||
</div>
|
||||
</td>
|
||||
<td>转换字节字符串为无符号整数值<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-string-byte-strtoimax.html"><span class="t-lines"><span>strtoimax</span><span>strtoumax</span></span></a></div>
|
||||
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div>
|
||||
</div>
|
||||
</td>
|
||||
<td>转换字节字符串为 <span class="t-lc"><a href="cpp-types-integer.html">std::intmax_t</a></span> 或 <span class="t-lc"><a href="cpp-types-integer.html">std::uintmax_t</a></span><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-utility-from_chars.html"><span class="t-lines"><span>from_chars</span></span></a></div>
|
||||
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx17">(C++17)</span></span></span></div>
|
||||
</div>
|
||||
</td>
|
||||
<td>转换字符序列到整数或浮点值<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-string-byte-atoi.html"><span class="t-lines"><span>atoi</span><span>atol</span><span>atoll</span></span></a></div>
|
||||
<div><span class="t-lines"><span></span><span></span><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div>
|
||||
</div>
|
||||
</td>
|
||||
<td>转换字节字符串为整数值<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-string-basic_string-to_string.html"><span class="t-lines"><span>to_string</span></span></a></div>
|
||||
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div>
|
||||
</div>
|
||||
</td>
|
||||
<td>转换整数或浮点值为 <code>string</code><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-string-basic_string-to_wstring.html"><span class="t-lines"><span>to_wstring</span></span></a></div>
|
||||
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div>
|
||||
</div>
|
||||
</td>
|
||||
<td>转换整数或浮点值为 <code>wstring</code><br />
|
||||
<span class="t-mark">(函数)</span></td>
|
||||
</tr>
|
||||
</table>
|
||||
</div>
|
||||
<div class="visualClear"></div>
|
||||
</div>
|
||||
</div>
|
||||
</div>
|
||||
</body>
|
||||
</html>
|
||||
Reference in New Issue
Block a user