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93 lines
6.7 KiB
HTML
93 lines
6.7 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<html>
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<head>
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<meta http-equiv="content-type" content="text/html; charset=UTF-8">
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<title>测试文件指针是否到了文件结束的位置</title>
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</head>
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<body class="docs"><div id="layout">
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<div id="layout-content"><div id="function.feof" class="refentry">
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<div class="refnamediv">
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<h1 class="refname">feof</h1>
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<p class="verinfo">(PHP 4, PHP 5, PHP 7)</p><p class="refpurpose"><span class="refname">feof</span> — <span class="dc-title">测试文件指针是否到了文件结束的位置</span></p>
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</div>
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<div class="refsect1 description" id="refsect1-function.feof-description">
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<h3 class="title">说明</h3>
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<div class="methodsynopsis dc-description">
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<span class="methodname"><strong>feof</strong></span>
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( <span class="methodparam"><span class="type">resource</span> <code class="parameter">$handle</code></span>
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) : <span class="type">bool</span></div>
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<p class="para rdfs-comment">
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测试文件指针是否到了文件结束的位。
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</p>
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</div>
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<div class="refsect1 parameters" id="refsect1-function.feof-parameters">
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<h3 class="title">参数</h3>
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<p class="para">
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<dl>
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<dt>
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<code class="parameter">handle</code></dt>
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<dd>
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<p class="para">文件指针必须是有效的，必须指向由
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<span class="function"><a href="fopen.html" class="function">fopen()</a></span> 或 <span class="function"><a href="fsockopen.html" class="function">fsockopen()</a></span> 成功打开的文件(并还未由 <span class="function"><a href="fclose.html" class="function">fclose()</a></span> 关闭)。</p>
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</dd>
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</dl>
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</p>
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</div>
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<div class="refsect1 returnvalues" id="refsect1-function.feof-returnvalues">
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<h3 class="title">返回值</h3>
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<p class="para">
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如果文件指针到了 EOF 或者出错时则返回 <strong><code>TRUE</code></strong>，否则返回一个错误（包括 socket
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超时），其它情况则返回 <strong><code>FALSE</code></strong>。
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</p>
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</div>
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<div class="refsect1 notes" id="refsect1-function.feof-notes">
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<h3 class="title">注释</h3>
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<div class="warning"><strong class="warning">Warning</strong>
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<p class="para">
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如果服务器没有关闭由 <span class="function"><a href="fsockopen.html" class="function">fsockopen()</a></span> 所打开的连接，<span class="function"><strong>feof()</strong></span>
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会一直等待直到超时。要解决这个问题可参见以下范例：
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<div class="example" id="example-2770">
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<p><strong>Example #1 处理 <span class="function"><strong>feof()</strong></span> 的超时</strong></p>
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<div class="example-contents">
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<div class="phpcode"><pre><span style="color: #000000">
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<span style="color: #0000BB"><?php<br /></span><span style="color: #007700">function </span><span style="color: #0000BB">safe_feof</span><span style="color: #007700">(</span><span style="color: #0000BB">$fp</span><span style="color: #007700">, &</span><span style="color: #0000BB">$start </span><span style="color: #007700">= </span><span style="color: #0000BB">NULL</span><span style="color: #007700">) {<br /> </span><span style="color: #0000BB">$start </span><span style="color: #007700">= </span><span style="color: #0000BB">microtime</span><span style="color: #007700">(</span><span style="color: #0000BB">true</span><span style="color: #007700">);<br /><br /> return </span><span style="color: #0000BB">feof</span><span style="color: #007700">(</span><span style="color: #0000BB">$fp</span><span style="color: #007700">);<br />}<br /><br /></span><span style="color: #FF8000">/* $fp 的赋值是由之前 fsockopen() 打开 */<br /><br /></span><span style="color: #0000BB">$start </span><span style="color: #007700">= </span><span style="color: #0000BB">NULL</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$timeout </span><span style="color: #007700">= </span><span style="color: #0000BB">ini_get</span><span style="color: #007700">(</span><span style="color: #DD0000">'default_socket_timeout'</span><span style="color: #007700">);<br /><br />while(!</span><span style="color: #0000BB">safe_feof</span><span style="color: #007700">(</span><span style="color: #0000BB">$fp</span><span style="color: #007700">, </span><span style="color: #0000BB">$start</span><span style="color: #007700">) && (</span><span style="color: #0000BB">microtime</span><span style="color: #007700">(</span><span style="color: #0000BB">true</span><span style="color: #007700">) - </span><span style="color: #0000BB">$start</span><span style="color: #007700">) < </span><span style="color: #0000BB">$timeout</span><span style="color: #007700">)<br />{<br /> </span><span style="color: #FF8000">/* Handle */<br /></span><span style="color: #007700">}<br /></span><span style="color: #0000BB">?></span>
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</span>
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</pre></div>
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</div>
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</div>
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</p>
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</div>
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<div class="warning"><strong class="warning">Warning</strong>
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<p class="para">
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如果传递的文件指针无效可能会陷入无限循环中，因为 <span class="function"><strong>feof()</strong></span> 不会返回 <strong><code>TRUE</code></strong>。
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<div class="example" id="example-2771">
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<p><strong>Example #2 使用无效文件指针的 <span class="function"><strong>feof()</strong></span> 例子 </strong></p>
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<div class="example-contents">
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<div class="phpcode"><pre><span style="color: #000000">
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<span style="color: #0000BB"><?php<br /></span><span style="color: #FF8000">// 如果文件不可读取或者不存在，fopen 函数返回 FALSE<br /></span><span style="color: #0000BB">$file </span><span style="color: #007700">= @</span><span style="color: #0000BB">fopen</span><span style="color: #007700">(</span><span style="color: #DD0000">"no_such_file"</span><span style="color: #007700">, </span><span style="color: #DD0000">"r"</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">// 来自 fopen 的 FALSE 会发出一条警告信息并在这里陷入无限循环<br /></span><span style="color: #007700">while (!</span><span style="color: #0000BB">feof</span><span style="color: #007700">(</span><span style="color: #0000BB">$file</span><span style="color: #007700">)) {<br />}<br /><br /></span><span style="color: #0000BB">fclose</span><span style="color: #007700">(</span><span style="color: #0000BB">$file</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span>
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</span>
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</pre></div>
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</div>
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</div>
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</p>
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</div>
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</div>
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</div></div></div></body></html> |