120 lines
8.0 KiB
HTML
120 lines
8.0 KiB
HTML
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<title>std::fgetc, std::getc</title>
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::</span>fgetc, <span style="font-size:0.7em; line-height:130%">std::</span>getc</h1>
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<div id="contentSub"><span class="subpages">< <a href="cpp.html">cpp</a>‎ | <a href="cpp-io.html">io</a>‎ | <a href="cpp-io-c.html">c</a></span></div>
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<div>定义于头文件 <code><a href="cpp-header-cstdio.html"><cstdio></a></code></div>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">int</span> fgetc<span class="br0">(</span> <a href="cpp-io-c.html"><span class="kw1875">std::<span class="me2">FILE</span></span></a><span class="sy2">*</span> stream <span class="br0">)</span><span class="sy4">;</span><br />
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<span class="kw4">int</span> getc<span class="br0">(</span> <a href="cpp-io-c.html"><span class="kw1875">std::<span class="me2">FILE</span></span></a><span class="sy2">*</span> stream <span class="br0">)</span><span class="sy4">;</span></span></div>
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<p>读取来自给定输入流的下个字符。</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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<td>stream</td>
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<td>-</td>
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<td>读取字符的来源</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>成功时为获得的字符，失败时为 <span class="t-lc"><a href="cpp-io-c.html">EOF</a></span> 。</p>
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<p>若文件尾条件导致失败，则另外设置 <code>stream</code> 上的<i>文件尾</i>指示器（见 <span class="t-lc"><a href="cpp-io-c-feof.html">std::feof()</a></span> ）。若某些其他错误导致失败，则设置 <code>stream</code> 上的<i>错误</i>指示器（见 <span class="t-lc"><a href="cpp-io-c-ferror.html">std::ferror()</a></span> ）。</p>
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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="cpp source-cpp">
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<pre class="de1"><span class="co2">#include <cstdio></span>
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<span class="co2">#include <cstdlib></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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FILE<span class="sy2">*</span> fp <span class="sy1">=</span> <a href="cpp-io-c-fopen.html"><span class="kw1813">std::<span class="me2">fopen</span></span></a><span class="br0">(</span><span class="st0">"test.txt"</span>, <span class="st0">"r"</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="kw1">if</span><span class="br0">(</span><span class="sy3">!</span>fp<span class="br0">)</span> <span class="br0">{</span>
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<a href="cpp-io-c-perror.html"><span class="kw1871">std::<span class="me2">perror</span></span></a><span class="br0">(</span><span class="st0">"File opening failed"</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="kw1">return</span> <a href="cpp-utility-program-EXIT_status.html"><span class="kw973">EXIT_FAILURE</span></a><span class="sy4">;</span>
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<span class="br0">}</span>
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<span class="kw4">int</span> c<span class="sy4">;</span> <span class="co1">// 注意：是 int 而非 char ，要求处理 EOF</span>
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<span class="kw1">while</span> <span class="br0">(</span><span class="br0">(</span>c <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">fgetc</span><span class="br0">(</span>fp<span class="br0">)</span><span class="br0">)</span> <span class="sy3">!</span><span class="sy1">=</span> <a href="cpp-io-c.html"><span class="kw1880">EOF</span></a><span class="br0">)</span> <span class="br0">{</span> <span class="co1">// 标准 C I/O 文件读取循环</span>
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<a href="cpp-io-c-putchar.html"><span class="kw1827">std::<span class="me2">putchar</span></span></a><span class="br0">(</span>c<span class="br0">)</span><span class="sy4">;</span>
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<span class="br0">}</span>
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<span class="kw1">if</span> <span class="br0">(</span><a href="cpp-io-c-ferror.html"><span class="kw1870">std::<span class="me2">ferror</span></span></a><span class="br0">(</span>fp<span class="br0">)</span><span class="br0">)</span>
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<a href="cpp-io-c-puts.html"><span class="kw1828">std::<span class="me2">puts</span></span></a><span class="br0">(</span><span class="st0">"I/O error when reading"</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="kw1">else</span> <span class="kw1">if</span> <span class="br0">(</span><a href="cpp-io-c-feof.html"><span class="kw1869">std::<span class="me2">feof</span></span></a><span class="br0">(</span>fp<span class="br0">)</span><span class="br0">)</span>
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<a href="cpp-io-c-puts.html"><span class="kw1828">std::<span class="me2">puts</span></span></a><span class="br0">(</span><span class="st0">"End of file reached successfully"</span><span class="br0">)</span><span class="sy4">;</span>
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<a href="cpp-io-c-fclose.html"><span class="kw1816">std::<span class="me2">fclose</span></span></a><span class="br0">(</span>fp<span class="br0">)</span><span class="sy4">;</span>
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<span class="br0">}</span></pre></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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<div class="t-dsc-member-div">
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<div><a href="cpp-io-c-gets.html"><span class="t-lines"><span>gets</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-mark-rev t-deprecated-cxx11">(C++11 中弃用)</span></span><span><span class="t-mark-rev t-until-cxx14">(C++14 中移除)</span></span></span></div>
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</td>
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<td>从 <span class="t-lc"><a href="cpp-io-c.html">stdin</a></span> 读取字符串<br />
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<span class="t-mark">(函数)</span></td>
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<div class="t-dsc-member-div">
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<div><a href="cpp-io-c-fputc.html"><span class="t-lines"><span>fputc</span><span>putc</span></span></a></div>
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<td>写字符到文件流<br />
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<span class="t-mark">(函数)</span></td>
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<div class="t-dsc-member-div">
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<div><a href="cpp-io-c-ungetc.html"><span class="t-lines"><span>ungetc</span></span></a></div>
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</div>
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<td>把字符放回文件流<br />
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<span class="t-mark">(函数)</span></td>
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<div class="visualClear"></div>
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