195 lines
16 KiB
HTML
195 lines
16 KiB
HTML
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<title>strtoimax, strtoumax</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-c_string_byte_strtoimax skin-cppreference2 action-view cpp-navbar">
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<h1 id="firstHeading" class="firstHeading">strtoimax, strtoumax</h1>
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<div id="bodyContent">
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<div id="contentSub"><span class="subpages">< <a href="c.html">c</a>‎ | <a href="c-string.html">string</a>‎ | <a href="c-string-byte.html">byte</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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<div>定义于头文件 <code><inttypes.h></code></div>
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<div><span class="mw-geshi c source-c"><a href="c-types-integer.html"><span class="kw118">intmax_t</span></a> strtoimax<span class="br0">(</span> <span class="kw4">const</span> <span class="kw4">char</span> <span class="sy2">*</span><span class="kw4">restrict</span> nptr,<br />
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<span class="kw4">char</span> <span class="sy2">**</span><span class="kw4">restrict</span> endptr, <span class="kw4">int</span> base <span class="br0">)</span><span class="sy4">;</span></span></div>
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<td class="t-dcl-nopad"></td>
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<td><span class="t-mark-rev t-since-c99">(C99 起)</span></td>
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<div><span class="mw-geshi c source-c"><a href="c-types-integer.html"><span class="kw132">uintmax_t</span></a> strtoumax<span class="br0">(</span> <span class="kw4">const</span> <span class="kw4">char</span> <span class="sy2">*</span><span class="kw4">restrict</span> nptr,<br />
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<span class="kw4">char</span> <span class="sy2">**</span><span class="kw4">restrict</span> endptr, <span class="kw4">int</span> base <span class="br0">)</span><span class="sy4">;</span></span></div>
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<td class="t-dcl-nopad"></td>
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<td><span class="t-mark-rev t-since-c99">(C99 起)</span></td>
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<td></td>
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<td></td>
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<td></td>
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<p>转译 <code>nptr</code> 所指向的字节字符串中的值。</p>
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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 c source-c"><span class="nu0">8</span></span></span> 或 <span class="t-c"><span class="mw-geshi c source-c">​<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 c source-c"><span class="nu0">16</span></span></span> 或 <span class="t-c"><span class="mw-geshi c source-c">​<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="c-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 c source-c">​<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="c-language-operator_arithmetic.html#.E4.B8.80.E5.85.83.E7.AE.97.E6.9C.AF">一元减</a>。</p>
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<p>此函数设置 <code>endptr</code> 所指向的指针指向最后一个转译字符的后一字符。若 <code>endptr</code> 为空指针，则忽略它。</p>
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<p>若 <code>nptr</code> 为空字符串或无期待的形式，则不进行转换，并（若 <code>enptr</code> 非空指针）将 <code>nptr</code> 存储于 <code>endptr</code> 所指向的对象。</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>指向要被转译的空终止字符串的指针</td>
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</tr>
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<tr class="t-par">
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<td>str_end</td>
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<td>-</td>
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<td>指向指向字符的指针的指针。</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>被转译整数值的<i>底</i></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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<ul>
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<li>若成功，则返回对应 <code>str</code> 内容的整数值。</li>
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<li>若整数值落在对应的返回类型范围外，则发生值域错误（设置 <span class="t-lc"><a href="c-error-errno.html">errno</a></span> 为 <span class="t-lc"><a href="c-error-errno_macros.html">ERANGE</a></span> ），并返回 <span class="t-lc"><a href="c-types-integer.html">INTMAX_MAX</a></span> 、 <span class="t-lc"><a href="c-types-integer.html">INTMAX_MIN</a></span> 、 <span class="t-lc"><a href="c-types-integer.html">UINTMAX_MAX</a></span> 或 <span class="t-c"><span class="mw-geshi c source-c">​<span class="nu0">0</span>​</span></span> 中的最接近者。</li>
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<li>若无法进行转换，则返回 <span class="t-c"><span class="mw-geshi c source-c">​<span class="nu0">0</span>​</span></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="c source-c">
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<pre class="de1"><span class="co2">#include <stdio.h></span>
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<span class="co2">#include <inttypes.h></span>
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<span class="co2">#include <errno.h></span>
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<span class="co2">#include <string.h></span>
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<span class="kw4">int</span> main<span class="br0">(</span><span class="kw4">void</span><span class="br0">)</span>
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<span class="br0">{</span>
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<span class="kw4">char</span><span class="sy2">*</span> endptr<span class="sy4">;</span>
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<a href="c-io-fprintf.html"><span class="kw849">printf</span></a><span class="br0">(</span><span class="st0">"%ld<span class="es1">\n</span>"</span>, strtoimax<span class="br0">(</span><span class="st0">" -123junk"</span>,<span class="sy3">&</span>endptr,<span class="nu0">10</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span> <span class="coMULTI">/* 底 10 */</span>
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<a href="c-io-fprintf.html"><span class="kw849">printf</span></a><span class="br0">(</span><span class="st0">"%ld<span class="es1">\n</span>"</span>, strtoimax<span class="br0">(</span><span class="st0">"11111111"</span>,<span class="sy3">&</span>endptr,<span class="nu0">2</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span> <span class="coMULTI">/* 底 2 */</span>
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<a href="c-io-fprintf.html"><span class="kw849">printf</span></a><span class="br0">(</span><span class="st0">"%ld<span class="es1">\n</span>"</span>, strtoimax<span class="br0">(</span><span class="st0">"XyZ"</span>,<span class="sy3">&</span>endptr,<span class="nu0">36</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span> <span class="coMULTI">/* 底 36 */</span>
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<a href="c-io-fprintf.html"><span class="kw849">printf</span></a><span class="br0">(</span><span class="st0">"%ld<span class="es1">\n</span>"</span>, strtoimax<span class="br0">(</span><span class="st0">"010"</span>,<span class="sy3">&</span>endptr,<span class="nu0">0</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span> <span class="coMULTI">/* 八进制自动检测 */</span>
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<a href="c-io-fprintf.html"><span class="kw849">printf</span></a><span class="br0">(</span><span class="st0">"%ld<span class="es1">\n</span>"</span>, strtoimax<span class="br0">(</span><span class="st0">"10"</span>,<span class="sy3">&</span>endptr,<span class="nu0">0</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span> <span class="coMULTI">/* 十进制自动检测 */</span>
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<a href="c-io-fprintf.html"><span class="kw849">printf</span></a><span class="br0">(</span><span class="st0">"%ld<span class="es1">\n</span>"</span>, strtoimax<span class="br0">(</span><span class="st0">"0x10"</span>,<span class="sy3">&</span>endptr,<span class="nu0">0</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span> <span class="coMULTI">/* 十六进制自动检测 */</span>
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<span class="coMULTI">/* 值域错误 */</span>
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<span class="coMULTI">/* LONG_MAX+1 --> LONG_MAX */</span>
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<span class="kw2">errno</span> <span class="sy1">=</span> <span class="nu0">0</span><span class="sy4">;</span>
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<a href="c-io-fprintf.html"><span class="kw849">printf</span></a><span class="br0">(</span><span class="st0">"%ld<span class="es1">\n</span>"</span>, strtoimax<span class="br0">(</span><span class="st0">"9223372036854775808"</span>,<span class="sy3">&</span>endptr,<span class="nu0">10</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
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<a href="c-io-fprintf.html"><span class="kw849">printf</span></a><span class="br0">(</span><span class="st0">"%s<span class="es1">\n</span>"</span>, <a href="c-string-byte-strerror.html"><span class="kw572">strerror</span></a><span class="br0">(</span><span class="kw2">errno</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="kw1">return</span> <span class="nu0">0</span><span class="sy4">;</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">-123
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255
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44027
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8
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10
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16
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9223372036854775807
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Numerical result out of range</pre></div>
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</div>
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</div>
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<h3><span class="mw-headline" id=".E5.BC.95.E7.94.A8">引用</span></h3>
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<div class="t-ref-std-11">
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<ul>
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<li>C11 标准（ISO/IEC 9899:2011）：</li>
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</ul>
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<dl>
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<dd>
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<ul>
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<li>7.8.2.3 The strtoimax and strtoumax functions (p: 219)</li>
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</ul>
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</dd>
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</dl>
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<div class="t-ref-std-c99">
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<ul>
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<li>C99 标准（ISO/IEC 9899:1999）：</li>
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</ul>
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<dl>
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<dd>
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<ul>
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<li>7.8.2.3 The strtoimax and strtoumax functions (p: 200)</li>
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</ul>
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</dd>
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</dl>
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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="c-string-wide-wcstoimax.html"><span class="t-lines"><span>wcstoimax</span><span>wcstoumax</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-mark-rev t-since-c99">(C99)</span></span><span><span class="t-mark-rev t-since-c99">(C99)</span></span></span></div>
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</div>
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</td>
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<td>将宽字符串转换成 <span class="t-c"><span class="mw-geshi c source-c"><a href="c-types-integer.html"><span class="kw118">intmax_t</span></a></span></span> 或 <span class="t-c"><span class="mw-geshi c source-c"><a href="c-types-integer.html"><span class="kw132">uintmax_t</span></a></span></span><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="c-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-c99">(C99)</span></span></span></div>
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</div>
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</td>
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<td>将字节字符串转换成整数值<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="c-string-byte-strtoul.html"><span class="t-lines"><span>strtoul</span> <span>strtoull</span></span></a></div>
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<div><span class="t-lines"><span></span><span><span class="t-mark-rev t-since-c99">(C99)</span></span></span></div>
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</div>
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</td>
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<td>将字节字符串转换成无符号整数值<br />
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<span class="t-mark">(函数)</span></td>
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</tr>
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</table>
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</div>
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</div>
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<div class="visualClear"></div>
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