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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::</span>atoi, <span style="font-size:0.7em; line-height:130%">std::</span>atol, <span style="font-size:0.7em; line-height:130%">std::</span>atoll</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-byte.html">byte</a></span></div>
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<div>&#23450;&#20041;&#20110;&#22836;&#25991;&#20214; <code><a href="cpp-header-cstdlib.html">&lt;cstdlib&gt;</a></code></div>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">int</span> &nbsp; &nbsp; &nbsp; atoi<span class="br0">(</span> <span class="kw4">const</span> <span class="kw4">char</span> <span class="sy2">*</span>str <span class="br0">)</span><span class="sy4">;</span></span></div>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">long</span> &nbsp; &nbsp; &nbsp;atol<span class="br0">(</span> <span class="kw4">const</span> <span class="kw4">char</span> <span class="sy2">*</span>str <span class="br0">)</span><span class="sy4">;</span></span></div>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">long</span> <span class="kw4">long</span> atoll<span class="br0">(</span> <span class="kw4">const</span> <span class="kw4">char</span> <span class="sy2">*</span>str <span class="br0">)</span><span class="sy4">;</span></span></div>
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<td><span class="t-mark-rev t-since-cxx11">(C++11 &#36215;)</span></td>
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<p>&#36716;&#35793; <code>str</code> &#25152;&#25351;&#21521;&#30340;&#23383;&#33410;&#23383;&#31526;&#20018;&#20013;&#30340;&#25972;&#25968;&#20540;&#12290;</p>
<p>&#33293;&#24323;&#20219;&#20309;&#31354;&#30333;&#31526;&#65292;&#30452;&#33267;&#25214;&#21040;&#39318;&#20010;&#38750;&#31354;&#30333;&#31526;&#65292;&#28982;&#21518;&#25509;&#25910;&#23613;&#21487;&#33021;&#22810;&#30340;&#23383;&#31526;&#20197;&#32452;&#25104;&#21512;&#27861;&#30340;&#25972;&#25968;&#34920;&#31034;&#65292;&#24182;&#36716;&#25442;&#20043;&#20026;&#25972;&#25968;&#20540;&#12290;&#21512;&#27861;&#30340;&#25972;&#25968;&#20540;&#21547;&#19979;&#21015;&#37096;&#20998;&#65306;</p>
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<li><span class="t-mark">(&#21487;&#36873;)</span> &#27491;&#25110;&#36127;&#21495;</li>
<li>&#25968;&#20301;</li>
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<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">&#21442;&#25968;</span></h3>
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<td>str</td>
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<td>&#25351;&#21521;&#35201;&#36716;&#35793;&#30340;&#31354;&#32456;&#27490;&#23383;&#33410;&#23383;&#31526;&#20018;&#30340;&#25351;&#38024;</td>
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<h3><span class="mw-headline" id=".E8.BF.94.E5.9B.9E.E5.80.BC">&#36820;&#22238;&#20540;</span></h3>
<p>&#25104;&#21151;&#26102;&#20026;&#23545;&#24212; <code>str</code> &#20869;&#23481;&#30340;&#25972;&#25968;&#20540;&#12290;&#33509;&#36716;&#25442;&#20986;&#30340;&#20540;&#33853;&#22312;&#23545;&#24212;&#36820;&#22238;&#31867;&#22411;&#30340;&#33539;&#22260;&#22806;&#65292;&#21017;&#36820;&#22238;&#20540;&#26410;&#23450;&#20041;&#12290;&#33509;&#19981;&#33021;&#36827;&#34892;&#36716;&#25442;&#65292;&#21017;&#36820;&#22238; <span class="t-c"><span class="mw-geshi cpp source-cpp">&#8203;<span class="nu0">0</span>&#8203;</span></span> &#12290;</p>
<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">&#31034;&#20363;</span></h3>
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<pre class="de1"><span class="co2">#include &lt;iostream&gt;</span>
<span class="co2">#include &lt;cstdlib&gt;</span>
<span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
<span class="br0">{</span>
<span class="kw4">const</span> <span class="kw4">char</span> <span class="sy2">*</span>str1 <span class="sy1">=</span> <span class="st0">&quot;42&quot;</span><span class="sy4">;</span>
<span class="kw4">const</span> <span class="kw4">char</span> <span class="sy2">*</span>str2 <span class="sy1">=</span> <span class="st0">&quot;3.14159&quot;</span><span class="sy4">;</span>
<span class="kw4">const</span> <span class="kw4">char</span> <span class="sy2">*</span>str3 <span class="sy1">=</span> <span class="st0">&quot;31337 with words&quot;</span><span class="sy4">;</span>
<span class="kw4">const</span> <span class="kw4">char</span> <span class="sy2">*</span>str4 <span class="sy1">=</span> <span class="st0">&quot;words and 2&quot;</span><span class="sy4">;</span>
<span class="kw4">int</span> num1 <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">atoi</span><span class="br0">(</span>str1<span class="br0">)</span><span class="sy4">;</span>
<span class="kw4">int</span> num2 <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">atoi</span><span class="br0">(</span>str2<span class="br0">)</span><span class="sy4">;</span>
<span class="kw4">int</span> num3 <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">atoi</span><span class="br0">(</span>str3<span class="br0">)</span><span class="sy4">;</span>
<span class="kw4">int</span> num4 <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">atoi</span><span class="br0">(</span>str4<span class="br0">)</span><span class="sy4">;</span>
<a href="cpp-io-cout.html"><span class="kw1755">std::<span class="me2">cout</span></span></a> <span class="sy1">&lt;&lt;</span> <span class="st0">&quot;std::atoi(<span class="es1">\&quot;</span>&quot;</span> <span class="sy1">&lt;&lt;</span> str1 <span class="sy1">&lt;&lt;</span> <span class="st0">&quot;<span class="es1">\&quot;</span>) is &quot;</span> <span class="sy1">&lt;&lt;</span> num1 <span class="sy1">&lt;&lt;</span> <span class="st0">&#39;<span class="es1">\n</span>&#39;</span><span class="sy4">;</span>
<a href="cpp-io-cout.html"><span class="kw1755">std::<span class="me2">cout</span></span></a> <span class="sy1">&lt;&lt;</span> <span class="st0">&quot;std::atoi(<span class="es1">\&quot;</span>&quot;</span> <span class="sy1">&lt;&lt;</span> str2 <span class="sy1">&lt;&lt;</span> <span class="st0">&quot;<span class="es1">\&quot;</span>) is &quot;</span> <span class="sy1">&lt;&lt;</span> num2 <span class="sy1">&lt;&lt;</span> <span class="st0">&#39;<span class="es1">\n</span>&#39;</span><span class="sy4">;</span>
<a href="cpp-io-cout.html"><span class="kw1755">std::<span class="me2">cout</span></span></a> <span class="sy1">&lt;&lt;</span> <span class="st0">&quot;std::atoi(<span class="es1">\&quot;</span>&quot;</span> <span class="sy1">&lt;&lt;</span> str3 <span class="sy1">&lt;&lt;</span> <span class="st0">&quot;<span class="es1">\&quot;</span>) is &quot;</span> <span class="sy1">&lt;&lt;</span> num3 <span class="sy1">&lt;&lt;</span> <span class="st0">&#39;<span class="es1">\n</span>&#39;</span><span class="sy4">;</span>
<a href="cpp-io-cout.html"><span class="kw1755">std::<span class="me2">cout</span></span></a> <span class="sy1">&lt;&lt;</span> <span class="st0">&quot;std::atoi(<span class="es1">\&quot;</span>&quot;</span> <span class="sy1">&lt;&lt;</span> str4 <span class="sy1">&lt;&lt;</span> <span class="st0">&quot;<span class="es1">\&quot;</span>) is &quot;</span> <span class="sy1">&lt;&lt;</span> num4 <span class="sy1">&lt;&lt;</span> <span class="st0">&#39;<span class="es1">\n</span>&#39;</span><span class="sy4">;</span>
<span class="br0">}</span></pre></div>
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<p>&#36755;&#20986;&#65306;</p>
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<pre class="de1">std::atoi(&quot;42&quot;) is 42
std::atoi(&quot;3.14159&quot;) is 3
std::atoi(&quot;31337 with words&quot;) is 31337
std::atoi(&quot;words and 2&quot;) is 0</pre></div>
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<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">&#21442;&#38405;</span></h3>
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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>
<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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<td>&#36716;&#25442;&#23383;&#31526;&#20018;&#20026;&#26377;&#31526;&#21495;&#25972;&#25968;<br />
<span class="t-mark">(&#20989;&#25968;)</span></td>
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<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>
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<td>&#36716;&#25442;&#23383;&#31526;&#20018;&#20026;&#26080;&#31526;&#21495;&#25972;&#25968;<br />
<span class="t-mark">(&#20989;&#25968;)</span></td>
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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>
<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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<td>&#36716;&#25442;&#23383;&#33410;&#23383;&#31526;&#20018;&#20026;&#25972;&#25968;&#20540;<br />
<span class="t-mark">(&#20989;&#25968;)</span></td>
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<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>
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<td>&#36716;&#25442;&#23383;&#33410;&#23383;&#31526;&#20018;&#20026;&#26080;&#31526;&#21495;&#25972;&#25968;&#20540;<br />
<span class="t-mark">(&#20989;&#25968;)</span></td>
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<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>
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<td>&#36716;&#25442;&#23383;&#33410;&#23383;&#31526;&#20018;&#20026; <span class="t-lc"><a href="cpp-types-integer.html">std::intmax_t</a></span> &#25110; <span class="t-lc"><a href="cpp-types-integer.html">std::uintmax_t</a></span><br />
<span class="t-mark">(&#20989;&#25968;)</span></td>
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<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>
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<td>&#36716;&#25442;&#23383;&#31526;&#24207;&#21015;&#21040;&#25972;&#25968;&#25110;&#28014;&#28857;&#20540;<br />
<span class="t-mark">(&#20989;&#25968;)</span></td>
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