134 lines
8.9 KiB
HTML
134 lines
8.9 KiB
HTML
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<title>std::istrstream::istrstream</title>
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::istrstream::</span>istrstream</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-istrstream.html">istrstream</a></span></div>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">explicit</span> istrstream<span class="br0">(</span><span class="kw4">const</span> <span class="kw4">char</span><span class="sy2">*</span> s<span class="br0">)</span><span class="sy4">;</span></span></div>
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<td>(1)</td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">explicit</span> istrstream<span class="br0">(</span><span class="kw4">char</span><span class="sy2">*</span> s<span class="br0">)</span><span class="sy4">;</span></span></div>
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<td>(2)</td>
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<div><span class="mw-geshi cpp source-cpp">istrstream<span class="br0">(</span><span class="kw4">const</span> <span class="kw4">char</span><span class="sy2">*</span> s, <a href="cpp-io-streamsize.html"><span class="kw1804">std::<span class="me2">streamsize</span></span></a> n<span class="br0">)</span><span class="sy4">;</span></span></div>
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<td>(3)</td>
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<div><span class="mw-geshi cpp source-cpp">istrstream<span class="br0">(</span><span class="kw4">char</span><span class="sy2">*</span> s, <a href="cpp-io-streamsize.html"><span class="kw1804">std::<span class="me2">streamsize</span></span></a> n<span class="br0">)</span><span class="sy4">;</span></span></div>
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<td>(4)</td>
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<td></td>
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<td></td>
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<p>构造新的 istrstream 及其底层 <span class="t-lc"><a href="cpp-io-strstreambuf.html">std::strstreambuf</a></span> 。</p>
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<div class="t-li1"><span class="t-li">1,2)</span> 通过调用 <span class="t-c"><span class="mw-geshi cpp source-cpp">strstreambuf<span class="br0">(</span>s,<span class="nu0">0</span><span class="br0">)</span></span></span> 构造底层 <span class="t-lc"><a href="cpp-io-strstreambuf.html">std::strstreambuf</a></span> ，并以该 strstreambuf 的地址初始化基类。若 <code>s</code> 不指向空终止数组的元素，则行为未定义。</div>
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<div class="t-li1"><span class="t-li">3,4)</span> 通过调用 <span class="t-c"><span class="mw-geshi cpp source-cpp">strstreambuf<span class="br0">(</span>s,n<span class="br0">)</span></span></span> 构造底层 <span class="t-lc"><a href="cpp-io-strstreambuf.html">std::strstreambuf</a></span> ，并以该 strstreambuf 的地址初始化基类。若 <code>s</code> 不指向长度至少为 <code>n</code> 个元素的数组的元素，则行为未定义。</div>
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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>s</td>
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<td>-</td>
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<td>要用作流内容的 C 字符串或字符数组</td>
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<td>n</td>
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<td>-</td>
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<td>数组大小</td>
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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 dir="ltr" class="mw-geshi" style="text-align: left;">
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<div class="cpp source-cpp">
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<pre class="de1"><span class="co2">#include <iostream></span>
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<span class="co2">#include <strstream></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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<a href="cpp-io-istrstream.html"><span class="kw1753">std::<span class="me2">istrstream</span></span></a> s1<span class="br0">(</span><span class="st0">"1 2 3"</span><span class="br0">)</span><span class="sy4">;</span> <span class="co1">// 字符串字面量</span>
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<span class="kw4">int</span> n1,n2,n3<span class="sy4">;</span>
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<span class="kw1">if</span><span class="br0">(</span>s1 <span class="sy1">>></span> n1 <span class="sy1">>></span> n2 <span class="sy1">>></span> n3<span class="br0">)</span>
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<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> n1 <span class="sy1"><<</span> <span class="st0">", "</span> <span class="sy1"><<</span> n2 <span class="sy1"><<</span> <span class="st0">", "</span> <span class="sy1"><<</span> n3 <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span><span class="sy4">;</span>
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<span class="kw4">char</span> arr<span class="br0">[</span><span class="br0">]</span> <span class="sy1">=</span> <span class="br0">{</span><span class="st0">'4'</span>, <span class="st0">' '</span>, <span class="st0">'5'</span>, <span class="st0">' '</span>, <span class="st0">'6'</span><span class="br0">}</span><span class="sy4">;</span>
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<a href="cpp-io-istrstream.html"><span class="kw1753">std::<span class="me2">istrstream</span></span></a> s2<span class="br0">(</span>arr, sizeof arr<span class="br0">)</span><span class="sy4">;</span>
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<span class="kw1">if</span><span class="br0">(</span>s2 <span class="sy1">>></span> n1 <span class="sy1">>></span> n2 <span class="sy1">>></span> n3<span class="br0">)</span>
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<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> n1 <span class="sy1"><<</span> <span class="st0">", "</span> <span class="sy1"><<</span> n2 <span class="sy1"><<</span> <span class="st0">", "</span> <span class="sy1"><<</span> n3 <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</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 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">1, 2, 3
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4, 5, 6</pre></div>
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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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<div class="t-dsc-member-div t-dsc-member-nobold-div">
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<div><a href="cpp-io-strstreambuf-strstreambuf.html"><span class="t-lines"><span>(构造函数)</span></span></a></div>
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</div>
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</td>
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<td>构造 strstreambuf 对象<br />
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<span class="t-mark">(<code>std::strstreambuf</code> 的公开成员函数)</span></td>
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<div class="t-dsc-member-div t-dsc-member-nobold-div">
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<div><a href="cpp-io-ostrstream-ostrstream.html"><span class="t-lines"><span>(构造函数)</span></span></a></div>
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</div>
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</td>
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<td>构造 strstream ，可选地分配缓冲区<br />
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<span class="t-mark">(<code>std::ostrstream</code> 的公开成员函数)</span></td>
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<div class="t-dsc-member-div t-dsc-member-nobold-div">
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<div><a href="cpp-io-strstream-strstream.html"><span class="t-lines"><span>(构造函数)</span></span></a></div>
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</div>
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</td>
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<td>构造 strstream ，可选地分配缓冲区<br />
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<span class="t-mark">(<code>std::strstream</code> 的公开成员函数)</span></td>
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</div>
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<div class="visualClear"></div>
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</div>
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