📄 function.stream-filter-prepend.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>Attach a filter to a stream</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="function.stream-filter-append.html">stream_filter_append</a></div> <div class="next" style="text-align: right; float: right;"><a href="function.stream-filter-register.html">stream_filter_register</a></div> <div class="up"><a href="ref.stream.html">Stream Functions</a></div> <div class="home"><a href="index.html">PHP Manual</a></div></div><hr /><div id="function.stream-filter-prepend" class="refentry"> <div class="refnamediv"> <h1 class="refname">stream_filter_prepend</h1> <p class="verinfo">(PHP 4 >= 4.3.0, PHP 5)</p><p class="refpurpose"><span class="refname">stream_filter_prepend</span> — <span class="dc-title">Attach a filter to a stream</span></p> </div> <div class="refsect1 unknown"> <h3 class="title">Description</h3> <div class="methodsynopsis dc-description"> <span class="type">resource</span> <span class="methodname"><b><b>stream_filter_prepend</b></b></span> ( <span class="methodparam"><span class="type">resource</span> <tt class="parameter">$stream</tt></span> , <span class="methodparam"><span class="type">string</span> <tt class="parameter">$filtername</tt></span> [, <span class="methodparam"><span class="type">int</span> <tt class="parameter">$read_write</tt></span> [, <span class="methodparam"><span class="type"><a href="language.pseudo-types.html#language.types.mixed" class="type mixed">mixed</a></span> <tt class="parameter">$params</tt></span> ]] )</div> <p class="para rdfs-comment"> Adds <i><tt class="parameter">filtername</tt></i> to the list of filters attached to <i><tt class="parameter">stream</tt></i>. This filter will be added with the specified <i><tt class="parameter">params</tt></i> to the <em class="emphasis">beginning</em> of the list and will therefore be called first during stream operations. To add a filter to the end of the list, use <a href="function.stream-filter-append.html" class="function">stream_filter_append()</a>. </p> <p class="para"> By default, <b>stream_filter_prepend()</b> will attach the filter to the <i>read filter chain</i> if the file was opened for reading (i.e. File Mode: <i>r</i>, and/or <i>+</i>). The filter will also be attached to the <i>write filter chain</i> if the file was opened for writing (i.e. File Mode: <i>w</i>, <i>a</i>, and/or <i>+</i>). <b><tt>STREAM_FILTER_READ</tt></b>, <b><tt>STREAM_FILTER_WRITE</tt></b>, and/or <b><tt>STREAM_FILTER_ALL</tt></b> can also be passed to the <i><tt class="parameter">read_write</tt></i> parameter to override this behavior. See <a href="function.stream-filter-append.html" class="function">stream_filter_append()</a> for an example of using this parameter. </p> <p class="para"> As of PHP 5.1.0, this function returns a resource which can be used to refer to this filter instance during a call to <a href="function.stream-filter-remove.html" class="function">stream_filter_remove()</a>. Prior to PHP 5.1.0, this function returns <b><tt>TRUE</tt></b> on success or <b><tt>FALSE</tt></b> on failure. </p> <blockquote><p><b class="note">Note</b>: <b>When using custom (user) filters</b><br /> <span class="simpara"> <a href="function.stream-filter-register.html" class="function">stream_filter_register()</a> must be called first in order to register the desired user filter to <i><tt class="parameter">filtername</tt></i>. </span> </p></blockquote> <blockquote><p><b class="note">Note</b>: <span class="simpara"> Stream data is read from resources (both local and remote) in chunks, with any unconsumed data kept in internal buffers. When a new filter is prepended to a stream, data in the internal buffers, which has already been processed through other filters will <em class="emphasis">not</em> be reprocessed through the new filter at that time. This differs from the behavior of <a href="function.stream-filter-append.html" class="function">stream_filter_append()</a>. </span> </p></blockquote> <p class="simpara"> See also <a href="function.stream-filter-register.html" class="function">stream_filter_register()</a>, and <a href="function.stream-filter-append.html" class="function">stream_filter_append()</a>. </p> </div></div><hr /><div style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="function.stream-filter-append.html">stream_filter_append</a></div> <div class="next" style="text-align: right; float: right;"><a href="function.stream-filter-register.html">stream_filter_register</a></div> <div class="up"><a href="ref.stream.html">Stream Functions</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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