118 lines
13 KiB
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118 lines
13 KiB
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<title>std::stoul, std::stoull</title>
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::</span>stoul, <span style="font-size:0.7em; line-height:130%">std::</span>stoull</h1>
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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>定义于头文件 <code><a href="cpp-header-string.html"><string></a></code></div>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">unsigned</span> <span class="kw4">long</span> stoul<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">unsigned</span> <span class="kw4">long</span> stoul<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>(1)</td>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span></td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">unsigned</span> <span class="kw4">long</span> <span class="kw4">long</span> stoull<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">unsigned</span> <span class="kw4">long</span> <span class="kw4">long</span> stoull<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>(2)</td>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span></td>
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<p>转译字符串 <code>str</code> 中的无符号整数值。</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-strtoul.html"><span class="kw1133">std::<span class="me2">strtoul</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-wcstoul.html"><span class="kw1203">std::<span class="me2">wcstoul</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-strtoul.html"><span class="kw1134">std::<span class="me2">strtoull</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-wcstoul.html"><span class="kw1204">std::<span class="me2">wcstoull</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 ）的无符号整数表示，并将它们转换成一个整数值。合法的无符号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>，它对无符号整数应用回卷规则。</p>
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<p>若 <code>pos</code> 不是空指针，则转换函数内部的 <code>ptr</code> 指针会接收首个 <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> 中未转换字符的地址，然后该字符的下标在计算后存储于 <code>*pos</code> ，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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<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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<td>pos</td>
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<td>-</td>
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<td>存储被处理字符数的整数的地址</td>
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<td>base</td>
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<td>-</td>
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<td>数字基底</td>
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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>转换到指定无符号整数类型的字符串。</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>若不能进行转换则抛出 <span class="t-lc"><a href="cpp-error-invalid_argument.html">std::invalid_argument</a></span></li>
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<li>若转换值会落在转换类型的范围之外，或底层函数（ std::strtoul 或 std::strtoull ）设 <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> 则抛出 <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=".E5.8F.82.E9.98.85">参阅</span></h3>
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<div class="t-dsc-member-div">
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<div><a href="cpp-string-basic_string-stol.html"><span class="t-lines"><span>stoi</span><span>stol</span><span>stoll</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>转换字符串为有符号整数<br />
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<span class="t-mark">(函数)</span></td>
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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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