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132 lines
6.3 KiB
HTML
132 lines
6.3 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>检查文件或目录是否存在</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.file-exists" class="refentry">
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<div class="refnamediv">
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<h1 class="refname">file_exists</h1>
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<p class="verinfo">(PHP 4, PHP 5, PHP 7)</p><p class="refpurpose"><span class="refname">file_exists</span> — <span class="dc-title">检查文件或目录是否存在</span></p>
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</div>
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<div class="refsect1 description" id="refsect1-function.file-exists-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>file_exists</strong></span>
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( <span class="methodparam"><span class="type">string</span> <code class="parameter">$filename</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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检查文件或目录是否存在。
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</p>
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</div>
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<div class="refsect1 parameters" id="refsect1-function.file-exists-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">filename</code></dt>
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<dd>
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<p class="para">
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文件或目录的路径。
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</p>
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<p class="para">
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在 Windows 中要用 <var class="filename">//computername/share/filename</var> 或者
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<var class="filename">\\computername\share\filename</var> 来检查网络中的共享文件。
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</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.file-exists-returnvalues">
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<h3 class="title">返回值</h3>
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<p class="para">
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如果由 <code class="parameter">filename</code> 指定的文件或目录存在则返回
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<strong><code>TRUE</code></strong>，否则返回 <strong><code>FALSE</code></strong>。
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</p>
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<blockquote class="note"><p><strong class="note">Note</strong>:
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<p class="para">
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This function will return <strong><code>FALSE</code></strong> for symlinks pointing to non-existing
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files.
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</p>
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</p></blockquote>
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<div class="warning"><strong class="warning">Warning</strong>
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<p class="para">
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如果因为<a href="features.safe_mode.html" class="link">安全模式</a>的限制而导致不能访问文件的话，该函数会返回
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<strong><code>FALSE</code></strong>。然而，可以使用
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<a href="include.html" class="link">include</a> 来包含，如果文件在
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<a href="ini.sect.safe-mode.html#ini.safe-mode-include-dir" class="link">safe_mode_include_dir</a>
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所指定的目录里。
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</p>
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</div>
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<blockquote class="note"><p><strong class="note">Note</strong>:
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<p class="para">
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The check is done using the real UID/GID instead of the effective one.
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</p>
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</p></blockquote>
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<blockquote class="note"><p><strong class="note">Note</strong>: <span class="simpara">
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因为 PHP 的整数类型是有符号整型而且很多平台使用 32 位整型，对 2GB
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以上的文件，一些文件系统函数可能返回无法预期的结果 。</span></p></blockquote>
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</div>
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<div class="refsect1 examples" id="refsect1-function.file-exists-examples">
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<h3 class="title">范例</h3>
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<p class="para">
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<div class="example" id="example-2777">
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<p><strong>Example #1 测试一个文件是否存在</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 />$filename </span><span style="color: #007700">= </span><span style="color: #DD0000">'/path/to/foo.txt'</span><span style="color: #007700">;<br /><br />if (</span><span style="color: #0000BB">file_exists</span><span style="color: #007700">(</span><span style="color: #0000BB">$filename</span><span style="color: #007700">)) {<br /> echo </span><span style="color: #DD0000">"The file </span><span style="color: #0000BB">$filename</span><span style="color: #DD0000"> exists"</span><span style="color: #007700">;<br />} else {<br /> echo </span><span style="color: #DD0000">"The file </span><span style="color: #0000BB">$filename</span><span style="color: #DD0000"> does not exist"</span><span style="color: #007700">;<br />}<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="refsect1 errors" id="refsect1-function.file-exists-errors">
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<h3 class="title">错误／异常</h3>
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<p class="para">
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失败时抛出<strong><code>E_WARNING</code></strong>警告。
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</p>
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</div>
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<div class="refsect1 notes" id="refsect1-function.file-exists-notes">
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<h3 class="title">注释</h3>
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<blockquote class="note"><p><strong class="note">Note</strong>: <span class="simpara">此函数的结果会被缓存。参见
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<span class="function"><a href="clearstatcache.html" class="function">clearstatcache()</a></span> 以获得更多细节。</span></p></blockquote>
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<div class="tip"><strong class="tip">Tip</strong><p class="simpara">自 PHP 5.0.0 起, 此函数也用于<em class="emphasis">某些</em>
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URL 包装器。请参见 <a href="wrappers.html" class="xref">支持的协议和封装协议</a>以获得支持 <span class="function"><a href="stat.html" class="function">stat()</a></span> 系列函数功能的包装器列表。</p></div>
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</div>
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<div class="refsect1 seealso" id="refsect1-function.file-exists-seealso">
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<h3 class="title">参见</h3>
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<p class="para">
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<ul class="simplelist">
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<li class="member"><span class="function"><a href="is_readable.html" class="function" rel="rdfs-seeAlso">is_readable()</a> - 判断给定文件名是否可读</span></li>
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<li class="member"><span class="function"><a href="is_writable.html" class="function" rel="rdfs-seeAlso">is_writable()</a> - 判断给定的文件名是否可写</span></li>
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<li class="member"><span class="function"><a href="is_file.html" class="function" rel="rdfs-seeAlso">is_file()</a> - 判断给定文件名是否为一个正常的文件</span></li>
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<li class="member"><span class="function"><a href="file.html" class="function" rel="rdfs-seeAlso">file()</a> - 把整个文件读入一个数组中</span></li>
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</ul>
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</p>
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</div>
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</div></div></div></body></html> |