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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::</span>stof, <span style="font-size:0.7em; line-height:130%">std::</span>stod, <span style="font-size:0.7em; line-height:130%">std::</span>stold</h1>
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<div id="contentSub"><span class="subpages">&lt; <a href="cpp.html">cpp</a>&lrm; | <a href="cpp-string.html">string</a>&lrm; | <a href="cpp-string-basic_string.html">basic string</a></span></div>
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<div>&#23450;&#20041;&#20110;&#22836;&#25991;&#20214; <code><a href="cpp-header-string.html">&lt;string&gt;</a></code></div>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">float</span> &nbsp; &nbsp; &nbsp; stof<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">&amp;</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="br0">)</span><span class="sy4">;</span><br />
<span class="kw4">float</span> &nbsp; &nbsp; &nbsp; stof<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">&amp;</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="br0">)</span><span class="sy4">;</span></span></div>
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<td>(1)</td>
<td><span class="t-mark-rev t-since-cxx11">(C++11 &#36215;)</span></td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">double</span> &nbsp; &nbsp; &nbsp;stod<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">&amp;</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="br0">)</span><span class="sy4">;</span><br />
<span class="kw4">double</span> &nbsp; &nbsp; &nbsp;stod<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">&amp;</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="br0">)</span><span class="sy4">;</span></span></div>
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<td>(2)</td>
<td><span class="t-mark-rev t-since-cxx11">(C++11 &#36215;)</span></td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">long</span> <span class="kw4">double</span> stold<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">&amp;</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="br0">)</span><span class="sy4">;</span><br />
<span class="kw4">long</span> <span class="kw4">double</span> stold<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">&amp;</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="br0">)</span><span class="sy4">;</span></span></div>
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<td>(3)</td>
<td><span class="t-mark-rev t-since-cxx11">(C++11 &#36215;)</span></td>
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<p>&#36716;&#35793; string <code>str</code> &#20013;&#30340;&#28014;&#28857;&#20540;&#12290;</p>
<div class="t-li1"><span class="t-li">1)</span> &#35843;&#29992; <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-string-byte-strtof.html"><span class="kw1135">std::<span class="me2">strtof</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">&amp;</span>ptr<span class="br0">)</span></span></span> &#25110; <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-string-wide-wcstof.html"><span class="kw1198">std::<span class="me2">wcstof</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">&amp;</span>ptr<span class="br0">)</span></span></span></div>
<div class="t-li1"><span class="t-li">2)</span> &#35843;&#29992; <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-string-byte-strtof.html"><span class="kw1136">std::<span class="me2">strtod</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">&amp;</span>ptr<span class="br0">)</span></span></span> &#25110; <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-string-wide-wcstof.html"><span class="kw1199">std::<span class="me2">wcstod</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">&amp;</span>ptr<span class="br0">)</span></span></span></div>
<div class="t-li1"><span class="t-li">3)</span> &#35843;&#29992; <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-string-byte-strtof.html"><span class="kw1137">std::<span class="me2">strtold</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">&amp;</span>ptr<span class="br0">)</span></span></span> &#25110; <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-string-wide-wcstof.html"><span class="kw1200">std::<span class="me2">wcstold</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">&amp;</span>ptr<span class="br0">)</span></span></span></div>
<p>&#20989;&#25968;&#20250;&#33293;&#24323;&#20219;&#20309;&#31354;&#30333;&#31526;&#65288;&#30001; <span class="t-c"><span class="mw-geshi cpp source-cpp">std<span class="sy4">::</span><span class="me2">isspace</span><span class="br0">(</span><span class="br0">)</span></span></span> &#30830;&#23450;&#65289;&#65292;&#30452;&#33267;&#25214;&#21040;&#39318;&#20010;&#38750;&#31354;&#30333;&#31526;&#12290;&#28982;&#21518;&#23427;&#20250;&#21462;&#29992;&#23613;&#21487;&#33021;&#22810;&#30340;&#23383;&#31526;&#65292;&#20197;&#26500;&#25104;&#21512;&#27861;&#30340;&#28014;&#28857;&#25968;&#34920;&#31034;&#65292;&#24182;&#23558;&#23427;&#20204;&#36716;&#25442;&#25104;&#28014;&#28857;&#20540;&#12290;&#21512;&#27861;&#30340;&#28014;&#28857;&#20540;&#21487;&#20197;&#20026;&#19979;&#21015;&#20043;&#19968;&#65306;</p>
<ul>
<li>&#21313;&#36827;&#21046;&#28014;&#28857;&#25968;&#34920;&#36798;&#24335;&#12290;&#23427;&#30001;&#19979;&#21015;&#37096;&#20998;&#32452;&#25104;&#65306;</li>
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<dd>
<ul>
<li><span class="t-mark">(&#21487;&#36873;)</span> &#27491;&#25110;&#36127;&#21495;</li>
<li>&#38750;&#31354;&#30340;&#21313;&#36827;&#21046;&#25968;&#23383;&#24207;&#21015;&#65292;&#21487;&#36873;&#22320;&#21253;&#21547;&#19968;&#20010;&#23567;&#25968;&#28857;&#23383;&#31526;&#65288;&#30001;&#24403;&#21069;&#30340; C <a href="cpp-locale-setlocale.html">&#26412;&#22320;&#29615;&#22659;</a>&#30830;&#23450;&#65289;&#65288;&#23450;&#20041;&#26377;&#25928;&#25968;&#23383;&#65289;</li>
<li><span class="t-mark">(&#21487;&#36873;)</span> <code><b>e</b></code> &#25110; <code><b>E</b></code> &#65292;&#24182;&#36319;&#38543;&#21487;&#36873;&#30340;&#27491;&#25110;&#36127;&#21495;&#65292;&#20197;&#21450;&#38750;&#31354;&#21313;&#36827;&#21046;&#25968;&#23383;&#24207;&#21015;&#65288;&#20197; 10 &#20026;&#24213;&#23450;&#20041;&#25351;&#25968;&#65289;</li>
</ul>
</dd>
</dl>
<ul>
<li>&#21313;&#20845;&#36827;&#21046;&#28014;&#28857;&#25968;&#34920;&#36798;&#24335;&#12290;&#23427;&#30001;&#19979;&#21015;&#37096;&#20998;&#32452;&#25104;&#65306;</li>
</ul>
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<dd>
<ul>
<li><span class="t-mark">(&#21487;&#36873;)</span> &#27491;&#25110;&#36127;&#21495;</li>
<li><code><b>0x</b></code> &#25110; <code><b>0X</b></code></li>
<li>&#38750;&#31354;&#30340;&#21313;&#20845;&#36827;&#21046;&#25968;&#23383;&#24207;&#21015;&#65292;&#36873;&#22320;&#21253;&#21547;&#19968;&#20010;&#23567;&#25968;&#28857;&#23383;&#31526;&#65288;&#30001;&#24403;&#21069;&#30340; C <a href="cpp-locale-setlocale.html">&#26412;&#22320;&#29615;&#22659;</a>&#30830;&#23450;&#65289;&#65288;&#23450;&#20041;&#26377;&#25928;&#25968;&#23383;&#65289;</li>
<li><span class="t-mark">(&#21487;&#36873;)</span> <code><b>p</b></code> &#25110; <code><b>P</b></code> &#65292;&#24182;&#36319;&#38543;&#21487;&#36873;&#30340;&#27491;&#25110;&#36127;&#21495;&#65292;&#20197;&#21450;&#38750;&#31354;&#21313;&#36827;&#21046;&#25968;&#23383;&#24207;&#21015;&#65288;&#20197; 2 &#20026;&#24213;&#23450;&#20041;&#25351;&#25968;&#65289;</li>
</ul>
</dd>
</dl>
<ul>
<li>&#26080;&#31351;&#22823;&#34920;&#36798;&#24335;&#12290;&#23427;&#30001;&#19979;&#21015;&#37096;&#20998;&#32452;&#25104;&#65306;</li>
</ul>
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<dd>
<ul>
<li><span class="t-mark">(&#21487;&#36873;)</span> &#27491;&#25110;&#36127;&#21495;</li>
<li><code><b>INF</b></code> &#25110; <code><b>INFINITY</b></code> &#65292;&#24573;&#30053;&#22823;&#23567;&#20889;</li>
</ul>
</dd>
</dl>
<ul>
<li>&#38750;&#25968;&#65288;NaN&#65289;&#34920;&#36798;&#24335;&#12290;&#23427;&#30001;&#19979;&#21015;&#37096;&#20998;&#32452;&#25104;&#65306;</li>
</ul>
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<dd>
<ul>
<li><span class="t-mark">(&#21487;&#36873;)</span> &#27491;&#25110;&#36127;&#21495;</li>
<li><code><b>NAN</b></code> &#25110; <code><b>NAN(</b></code><i>char_sequence</i><code><b>)</b></code> &#65292;&#24573;&#30053; <code><b>NAN</b></code> &#37096;&#20998;&#30340;&#22823;&#23567;&#20889;&#12290; <i>char_sequence</i> &#21482;&#33021;&#30001;&#25968;&#23383;&#12289;&#25289;&#19969;&#23383;&#27597;&#21644;&#19979;&#21010;&#32447;&#26500;&#25104;&#12290;&#32467;&#26524;&#26159;&#19968;&#20010;&#38745;&#24577;&#30340; NaN &#28014;&#28857;&#20540;&#12290;</li>
</ul>
</dd>
</dl>
<ul>
<li>&#20219;&#20309;&#20854;&#20182;&#21487;&#30001;&#24403;&#21069; C <a href="cpp-locale-setlocale.html">&#26412;&#22320;&#29615;&#22659;</a>&#25509;&#21463;&#30340;&#34920;&#36798;&#24335;</li>
</ul>
<p>&#33509; <code>pos</code> &#19981;&#26159;&#31354;&#25351;&#38024;&#65292;&#21017;&#23545;&#20110;&#36716;&#25442;&#20989;&#25968;&#20026;&#20869;&#37096;&#30340;&#25351;&#38024; <code>ptr</code> &#23558;&#25509;&#21463; <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> &#20013;&#39318;&#20010;&#26410;&#36716;&#25442;&#23383;&#31526;&#30340;&#22320;&#22336;&#65292;&#28982;&#21518;&#35745;&#31639;&#35813;&#23383;&#31526;&#30340;&#19979;&#26631;&#24182;&#23384;&#20648;&#20043;&#20110; <code>*pos</code> &#65292;&#32473;&#20986;&#36716;&#25442;&#22788;&#29702;&#30340;&#23383;&#31526;&#25968;&#12290;</p>
<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">&#21442;&#25968;</span></h3>
<table class="t-par-begin">
<tr class="t-par">
<td>str</td>
<td>-</td>
<td>&#35201;&#36716;&#25442;&#30340; string</td>
</tr>
<tr class="t-par">
<td>pos</td>
<td>-</td>
<td>&#23384;&#20648;&#24050;&#22788;&#29702;&#23383;&#31526;&#25968;&#30340;&#25972;&#25968;&#30340;&#22320;&#22336;</td>
</tr>
</table>
<h3><span class="mw-headline" id=".E8.BF.94.E5.9B.9E.E5.80.BC">&#36820;&#22238;&#20540;</span></h3>
<p>&#36716;&#25442;&#20026;&#25351;&#23450;&#28014;&#28857;&#31867;&#22411;&#30340;&#23383;&#31526;&#20018;&#12290;</p>
<h3><span class="mw-headline" id=".E5.BC.82.E5.B8.B8">&#24322;&#24120;</span></h3>
<p>&#33509;&#19981;&#33021;&#36827;&#34892;&#36716;&#25442;&#21017;&#20026; <span class="t-lc"><a href="cpp-error-invalid_argument.html">std::invalid_argument</a></span> &#12290;</p>
<p>&#33509;&#36716;&#25442;&#21518;&#30340;&#20540;&#20250;&#33853;&#22312;&#32467;&#26524;&#31867;&#22411;&#30340;&#33539;&#22260;&#22806;&#65292;&#25110;&#33509;&#24213;&#23618;&#20989;&#25968;&#65288; <code>strtof</code> &#12289; <code>strtod</code> &#25110; <code>strtold</code> &#65289;&#35774;&#32622; <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">errno</span></span></span> &#20026; <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> &#21017;&#20026; <span class="t-lc"><a href="cpp-error-out_of_range.html">std::out_of_range</a></span> &#12290;</p>
<h3><span class="mw-headline" id=".E7.BC.BA.E9.99.B7.E6.8A.A5.E5.91.8A">&#32570;&#38519;&#25253;&#21578;</span></h3>
<p>&#19979;&#21015;&#26356;&#25913;&#34892;&#20026;&#30340;&#32570;&#38519;&#25253;&#21578;&#36861;&#28335;&#22320;&#24212;&#29992;&#20110;&#20197;&#21069;&#20986;&#29256;&#30340; C++ &#26631;&#20934;&#12290;</p>
<table class="dsctable" style="font-size:0.8em">
<tr>
<th>DR</th>
<th>&#24212;&#29992;&#20110;</th>
<th>&#20986;&#29256;&#26102;&#30340;&#34892;&#20026;</th>
<th>&#27491;&#30830;&#34892;&#20026;</th>
</tr>
<tr>
<td><a rel="nofollow" class="external text" href="https://cplusplus.github.io/LWG/issue2403">LWG 2403</a></td>
<td>C++11</td>
<td><code>stof</code> &#35843;&#29992; <span class="t-lc"><a href="cpp-string-byte-strtof.html">std::strtod</a></span> &#25110; <span class="t-lc"><a href="cpp-string-wide-wcstof.html">std::wcstod</a></span></td>
<td><code>stof</code> &#35843;&#29992; <span class="t-lc"><a href="cpp-string-byte-strtof.html">std::strtof</a></span> &#25110; <span class="t-lc"><a href="cpp-string-wide-wcstof.html">std::wcstof</a></span></td>
</tr>
</table>
<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">&#21442;&#38405;</span></h3>
<table class="t-dsc-begin">
<tr class="t-dsc">
<td>
<div class="t-dsc-member-div">
<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>
<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>
</div>
</td>
<td>&#36716;&#25442;&#23383;&#31526;&#20018;&#20026;&#26377;&#31526;&#21495;&#25972;&#25968;<br />
<span class="t-mark">(&#20989;&#25968;)</span></td>
</tr>
<tr class="t-dsc">
<td>
<div class="t-dsc-member-div">
<div><a href="cpp-string-basic_string-stoul.html"><span class="t-lines"><span>stoul</span><span>stoull</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>&#36716;&#25442;&#23383;&#31526;&#20018;&#20026;&#26080;&#31526;&#21495;&#25972;&#25968;<br />
<span class="t-mark">(&#20989;&#25968;)</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>&#36716;&#25442;&#23383;&#31526;&#24207;&#21015;&#21040;&#25972;&#25968;&#25110;&#28014;&#28857;&#20540;<br />
<span class="t-mark">(&#20989;&#25968;)</span></td>
</tr>
</table>
</div>
<div class="visualClear"></div>
</div>
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