107 lines
6.9 KiB
HTML
107 lines
6.9 KiB
HTML
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<title>std::fputc, std::putc</title>
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::</span>fputc, <span style="font-size:0.7em; line-height:130%">std::</span>putc</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> fputc<span class="br0">(</span> <span class="kw4">int</span> ch, <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> putc<span class="br0">(</span> <span class="kw4">int</span> ch, <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>写入字符 <code>ch</code> 到给定输出流 <code>stream</code> 。</p>
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<p>在内部,在写入前将字符转换为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">unsigned</span> <span class="kw4">char</span></span></span> 。</p>
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<p>C 中, <span class="t-c"><span class="mw-geshi cpp source-cpp">putc<span class="br0">(</span><span class="br0">)</span></span></span> 可以实现为宏,而这在 C++ 中被禁止。从而调用 <span class="t-c"><span class="mw-geshi cpp source-cpp">std<span class="sy4">::</span><span class="me2">fputc</span><span class="br0">(</span><span class="br0">)</span></span></span> 和 <span class="t-c"><span class="mw-geshi cpp source-cpp">std<span class="sy4">::</span><span class="me2">putc</span><span class="br0">(</span><span class="br0">)</span></span></span> 始终拥有相同效果。</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>ch</td>
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<td>-</td>
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<td>要写入的字符</td>
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<tr class="t-par">
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<td>stream</td>
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<td>-</td>
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<td>输出流</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,返回被写入字符。</p>
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<p>失败时,返回 <span class="t-lc"><a href="cpp-io-c.html">EOF</a></span> 并设置 <span class="t-lc">stream</span> 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="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
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<span class="br0">{</span>
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<span class="kw1">for</span> <span class="br0">(</span><span class="kw4">char</span> c <span class="sy1">=</span> <span class="st0">'a'</span><span class="sy4">;</span> c <span class="sy3">!</span><span class="sy1">=</span> <span class="st0">'z'</span><span class="sy4">;</span> c<span class="sy2">++</span><span class="br0">)</span>
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std<span class="sy4">::</span><span class="me2">putc</span><span class="br0">(</span>c, <span class="kw2">stdout</span><span class="br0">)</span><span class="sy4">;</span>
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std<span class="sy4">::</span><span class="me2">putc</span><span class="br0">(</span><span class="st0">'<span class="es1">\n</span>'</span>, <span class="kw2">stdout</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="co1">// putchar 的返回值不等于参数</span>
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<span class="kw4">int</span> r <span class="sy1">=</span> <span class="nu12">0x1070</span><span class="sy4">;</span>
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<a href="cpp-io-c-fprintf.html"><span class="kw1843">std::<span class="me2">printf</span></span></a><span class="br0">(</span><span class="st0">"<span class="es1">\n</span>0x%x<span class="es1">\n</span>"</span>, r<span class="br0">)</span><span class="sy4">;</span>
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r <span class="sy1">=</span> <a href="cpp-io-c-putchar.html"><span class="kw1827">std::<span class="me2">putchar</span></span></a><span class="br0">(</span>r<span class="br0">)</span><span class="sy4">;</span>
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<a href="cpp-io-c-fprintf.html"><span class="kw1843">std::<span class="me2">printf</span></span></a><span class="br0">(</span><span class="st0">"<span class="es1">\n</span>0x%x<span class="es1">\n</span>"</span>, r<span class="br0">)</span><span class="sy4">;</span>
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<span class="br0">}</span></pre></div>
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<p>输出:</p>
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<div class="text source-text">
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<pre class="de1">abcdefghijklmnopqrstuvwxy
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0x1070
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p
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0x70</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-putchar.html"><span class="t-lines"><span>putchar</span></span></a></div>
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<td>写字符到 <span class="t-lc"><a href="cpp-io-c.html">stdout</a></span><br />
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<span class="t-mark">(函数)</span></td>
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