filters.html
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html> <head> <title>List of Available Filters</title> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> </head> <body><div style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="wrappers.expect.html">Process Interaction Streams</a></div> <div class="next" style="text-align: right; float: right;"><a href="filters.convert.html">Conversion Filters</a></div> <div class="up"><a href="appendices.html">Appendices</a></div> <div class="home"><a href="index.html">PHP Manual</a></div></div><hr /><div> <h1>List of Available Filters</h1><h2>Table of Contents</h2><ul class="chunklist chunklist_appendix"><li><a href="filters.convert.html">Conversion Filters</a></li><li><a href="filters.compression.html">Compression Filters</a></li><li><a href="filters.encryption.html">Encryption Filters</a></li></ul> <p class="para"> The following is a list of a few built-in stream filters for use with <a href="function.stream-filter-append.html" class="function">stream_filter_append()</a>. Your version of PHP may have more filters (or fewer) than those listed here. </p> <p class="para"> It is worth noting a slight asymmetry between <a href="function.stream-filter-append.html" class="function">stream_filter_append()</a> and <a href="function.stream-filter-prepend.html" class="function">stream_filter_prepend()</a>. Every PHP stream contains a small <em class="emphasis">read buffer</em> where it stores blocks of data retrieved from the filesystem or other resource in order to process data in the most efficient manner. As soon as data is pulled from the resource into the stream's internal buffer, it is immediately processed through any attached filters whether the PHP application is actually ready for the data or not. If data is sitting in the read buffer when a filter is <em class="emphasis">appended</em>, this data will be immediately processed through that filter making the fact that it was sitting in the buffer seem transparent. However, if data is sitting in the read buffer when a filter is <em class="emphasis">prepended</em>, this data will <em class="emphasis">NOT</em> be processed through that filter. It will instead wait until the next block of data is retrieved from the resource. </p> <p class="para"> For a list of filters installed in your version of PHP use <a href="function.stream-get-filters.html" class="function">stream_get_filters()</a>. </p> <div id="filters.string" class="section"> <h2 class="title">String Filters</h2> <p class="simpara"> Each of these filters does precisely what their name implies and correspond to the behavior of a built-in php string handling function. For more information on a given filter, refer to the manual page for the corresponding function. </p> <p class="simpara"> <i>string.rot13</i> (since PHP 4.3.0) Use of this filter is equivalent to processing all stream data through the <a href="function.str-rot13.html" class="function">str_rot13()</a> function. </p> <div class="example"> <p><b>Example #1 string.rot13</b></p> <div class="example-contents"><div class="phpcode"><code><span style="color: #000000"><span style="color: #0000BB"><?php<br />$fp </span><span style="color: #007700">= </span><span style="color: #0000BB">fopen</span><span style="color: #007700">(</span><span style="color: #DD0000">'php://output'</span><span style="color: #007700">, </span><span style="color: #DD0000">'w'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">stream_filter_append</span><span style="color: #007700">(</span><span style="color: #0000BB">$fp</span><span style="color: #007700">, </span><span style="color: #DD0000">'string.rot13'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">fwrite</span><span style="color: #007700">(</span><span style="color: #0000BB">$fp</span><span style="color: #007700">, </span><span style="color: #DD0000">"This is a test.\n"</span><span style="color: #007700">);<br /></span><span style="color: #FF8000">/* Outputs: Guvf vf n grfg. */<br /></span><span style="color: #0000BB">?></span></span></code></div> </div> </div> <p class="simpara"> <i>string.toupper</i> (since PHP 5.0.0) Use of this filter is equivalent to processing all stream data through the <a href="function.strtoupper.html" class="function">strtoupper()</a> function. </p> <div class="example"> <p><b>Example #2 string.toupper</b></p> <div class="example-contents"><div class="phpcode"><code><span style="color: #000000"><span style="color: #0000BB"><?php<br />$fp </span><span style="color: #007700">= </span><span style="color: #0000BB">fopen</span><span style="color: #007700">(</span><span style="color: #DD0000">'php://output'</span><span style="color: #007700">, </span><span style="color: #DD0000">'w'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">stream_filter_append</span><span style="color: #007700">(</span><span style="color: #0000BB">$fp</span><span style="color: #007700">, </span><span style="color: #DD0000">'string.toupper'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">fwrite</span><span style="color: #007700">(</span><span style="color: #0000BB">$fp</span><span style="color: #007700">, </span><span style="color: #DD0000">"This is a test.\n"</span><span style="color: #007700">);<br /></span><span style="color: #FF8000">/* Outputs: THIS IS A TEST. */<br /></span><span style="color: #0000BB">?></span></span></code></div> </div> </div> <p class="simpara"> <i>string.tolower</i> (since PHP 5.0.0) Use of this filter is equivalent to processing all stream data through the <a href="function.strtolower.html" class="function">strtolower()</a> function. </p> <div class="example"> <p><b>Example #3 string.tolower</b></p> <div class="example-contents"><div class="phpcode"><code><span style="color: #000000"><span style="color: #0000BB"><?php<br />$fp </span><span style="color: #007700">= </span><span style="color: #0000BB">fopen</span><span style="color: #007700">(</span><span style="color: #DD0000">'php://output'</span><span style="color: #007700">, </span><span style="color: #DD0000">'w'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">stream_filter_append</span><span style="color: #007700">(</span><span style="color: #0000BB">$fp</span><span style="color: #007700">, </span><span style="color: #DD0000">'string.tolower'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">fwrite</span><span style="color: #007700">(</span><span style="color: #0000BB">$fp</span><span style="color: #007700">, </span><span style="color: #DD0000">"This is a test.\n"</span><span style="color: #007700">);<br /></span><span style="color: #FF8000">/* Outputs: this is a test. */<br /></span><span style="color: #0000BB">?></span></span></code></div> </div> </div> <p class="simpara"> <i>string.strip_tags</i> (since PHP 5.0.0) Use of this filter is equivalent to processing all stream data through the <a href="function.strip-tags.html" class="function">strip_tags()</a> function. It accepts parameters in one of two forms: Either as a string containing a list of tags similar to the second parameter of the <a href="function.strip-tags.html" class="function">strip_tags()</a> function, or as an array of tag names. </p> <div class="example"> <p><b>Example #4 string.strip_tags</b></p> <div class="example-contents"><div class="phpcode"><code><span style="color: #000000"><span style="color: #0000BB"><?php<br />$fp </span><span style="color: #007700">= </span><span style="color: #0000BB">fopen</span><span style="color: #007700">(</span><span style="color: #DD0000">'php://output'</span><span style="color: #007700">, </span><span style="color: #DD0000">'w'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">stream_filter_append</span><span style="color: #007700">(</span><span style="color: #0000BB">$fp</span><span style="color: #007700">, </span><span style="color: #DD0000">'string.strip_tags'</span><span style="color: #007700">, </span><span style="color: #0000BB">STREAM_FILTER_WRITE</span><span style="color: #007700">, </span><span style="color: #DD0000">"<b><i><u>"</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">fwrite</span><span style="color: #007700">(</span><span style="color: #0000BB">$fp</span><span style="color: #007700">, </span><span style="color: #DD0000">"<b>bolded text</b> enlarged to a <h1>level 1 heading</h1>\n"</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">fclose</span><span style="color: #007700">(</span><span style="color: #0000BB">$fp</span><span style="color: #007700">);<br /></span><span style="color: #FF8000">/* Outputs: <b>bolded text</b> enlarged to a level 1 heading */<br /><br /></span><span style="color: #0000BB">$fp </span><span style="color: #007700">= </span><span style="color: #0000BB">fopen</span><span style="color: #007700">(</span><span style="color: #DD0000">'php://output'</span><span style="color: #007700">, </span><span style="color: #DD0000">'w'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">stream_filter_append</span><span style="color: #007700">(</span><span style="color: #0000BB">$fp</span><span style="color: #007700">, </span><span style="color: #DD0000">'string.strip_tags'</span><span style="color: #007700">, </span><span style="color: #0000BB">STREAM_FILTER_WRITE</span><span style="color: #007700">, array(</span><span style="color: #DD0000">'b'</span><span style="color: #007700">,</span><span style="color: #DD0000">'i'</span><span style="color: #007700">,</span><span style="color: #DD0000">'u'</span><span style="color: #007700">));<br /></span><span style="color: #0000BB">fwrite</span><span style="color: #007700">(</span><span style="color: #0000BB">$fp</span><span style="color: #007700">, </span><span style="color: #DD0000">"<b>bolded text</b> enlarged to a <h1>level 1 heading</h1>\n"</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">fclose</span><span style="color: #007700">(</span><span style="color: #0000BB">$fp</span><span style="color: #007700">);<br /></span><span style="color: #FF8000">/* Outputs: <b>bolded text</b> enlarged to a level 1 heading */<br /></span><span style="color: #0000BB">?></span></span></code></div> </div> </div> </div> </div><hr /><div style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="wrappers.expect.html">Process Interaction Streams</a></div> <div class="next" style="text-align: right; float: right;"><a href="filters.convert.html">Conversion Filters</a></div> <div class="up"><a href="appendices.html">Appendices</a></div> <div class="home"><a href="index.html">PHP Manual</a></div></div></body></html>⌨️ 快捷键说明
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