function.extract.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>Import variables into the current symbol table from an array</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.end.html">end</a></div> <div class="next" style="text-align: right; float: right;"><a href="function.in-array.html">in_array</a></div> <div class="up"><a href="ref.array.html">Array Functions</a></div> <div class="home"><a href="index.html">PHP Manual</a></div></div><hr /><div id="function.extract" class="refentry"> <div class="refnamediv"> <h1 class="refname">extract</h1> <p class="verinfo">(PHP 4, PHP 5)</p><p class="refpurpose"><span class="refname">extract</span> — <span class="dc-title">Import variables into the current symbol table from an array</span></p> </div> <div class="refsect1 description"> <h3 class="title">Description</h3> <div class="methodsynopsis dc-description"> <span class="type">int</span> <span class="methodname"><b><b>extract</b></b></span> ( <span class="methodparam"><span class="type">array</span> <tt class="parameter">$var_array</tt></span> [, <span class="methodparam"><span class="type">int</span> <tt class="parameter">$extract_type</tt></span> [, <span class="methodparam"><span class="type">string</span> <tt class="parameter">$prefix</tt></span> ]] )</div> <p class="para rdfs-comment"> Import variables from an array into the current symbol table. </p> <p class="para"> <b>extract()</b> checks each key to see whether it has a valid variable name. It also checks for collisions with existing variables in the symbol table. </p> </div> <div class="refsect1 parameters"> <h3 class="title">Parameters</h3> <p class="para"> <dl> <dt> <span class="term"><i><tt class="parameter">var_array</tt></i></span> <dd> <p class="para"> An associative array. This function treats keys as variable names and values as variable values. For each key/value pair it will create a variable in the current symbol table, subject to <i><tt class="parameter">extract_type</tt></i> and <i><tt class="parameter">prefix</tt></i> parameters. </p> <p class="para"> You must use an associative array, a numerically indexed array will not produce results unless you use <b><tt>EXTR_PREFIX_ALL</tt></b> or <b><tt>EXTR_PREFIX_INVALID</tt></b>. </p> </dd> </dt> <dt> <span class="term"><i><tt class="parameter">extract_type</tt></i></span> <dd> <p class="para"> The way invalid/numeric keys and collisions are treated is determined by the <i><tt class="parameter">extract_type</tt></i>. It can be one of the following values: <dl> <dt> <span class="term"><b><tt>EXTR_OVERWRITE</tt></b></span> <dd> <span class="simpara"> If there is a collision, overwrite the existing variable. </span> </dd> </dt> <dt> <span class="term"><b><tt>EXTR_SKIP</tt></b></span> <dd> <span class="simpara"> If there is a collision, don't overwrite the existing variable. </span> </dd> </dt> <dt> <span class="term"><b><tt>EXTR_PREFIX_SAME</tt></b></span> <dd> <span class="simpara">If there is a collision, prefix the variable name with <i><tt class="parameter">prefix</tt></i>. </span> </dd> </dt> <dt> <span class="term"><b><tt>EXTR_PREFIX_ALL</tt></b></span> <dd> <span class="simpara"> Prefix all variable names with <i><tt class="parameter">prefix</tt></i>. </span> </dd> </dt> <dt> <span class="term"><b><tt>EXTR_PREFIX_INVALID</tt></b></span> <dd> <span class="simpara"> Only prefix invalid/numeric variable names with <i><tt class="parameter">prefix</tt></i>. </span> </dd> </dt> <dt> <span class="term"><b><tt>EXTR_IF_EXISTS</tt></b></span> <dd> <span class="simpara"> Only overwrite the variable if it already exists in the current symbol table, otherwise do nothing. This is useful for defining a list of valid variables and then extracting only those variables you have defined out of <var class="varname"><a href="reserved.variables.request.html" class="classname">$_REQUEST</a></var>, for example. </span> </dd> </dt> <dt> <span class="term"><b><tt>EXTR_PREFIX_IF_EXISTS</tt></b></span> <dd> <span class="simpara"> Only create prefixed variable names if the non-prefixed version of the same variable exists in the current symbol table. </span> </dd> </dt> <dt> <span class="term"><b><tt>EXTR_REFS</tt></b></span> <dd> <span class="simpara"> Extracts variables as references. This effectively means that the values of the imported variables are still referencing the values of the <i><tt class="parameter">var_array</tt></i> parameter. You can use this flag on its own or combine it with any other flag by OR'ing the <i><tt class="parameter">extract_type</tt></i>. </span> </dd> </dt> </dl> </p> <p class="para"> If <i><tt class="parameter">extract_type</tt></i> is not specified, it is assumed to be <b><tt>EXTR_OVERWRITE</tt></b>. </p> </dd> </dt> <dt> <span class="term"><i><tt class="parameter">prefix</tt></i></span> <dd> <p class="para"> Note that <i><tt class="parameter">prefix</tt></i> is only required if <i><tt class="parameter">extract_type</tt></i> is <b><tt>EXTR_PREFIX_SAME</tt></b>, <b><tt>EXTR_PREFIX_ALL</tt></b>, <b><tt>EXTR_PREFIX_INVALID</tt></b> or <b><tt>EXTR_PREFIX_IF_EXISTS</tt></b>. If the prefixed result is not a valid variable name, it is not imported into the symbol table. Prefixes are automatically separated from the array key by an underscore character. </p> </dd> </dt> </dl> </p> </div> <div class="refsect1 returnvalues"> <h3 class="title">Return Values</h3> <p class="para"> Returns the number of variables successfully imported into the symbol table. </p> </div> <div class="refsect1 changelog"> <h3 class="title">ChangeLog</h3> <p class="para"> <table class="informaltable"> <colgroup> <thead valign="middle"> <tr valign="middle"> <th colspan="1">Version</th> <th colspan="1">Description</th> </tr> </thead> <tbody valign="middle" class="tbody"> <tr valign="middle"> <td colspan="1" rowspan="1" align="left">4.3.0</td> <td colspan="1" rowspan="1" align="left"> <b><tt>EXTR_REFS</tt></b> was added. </td> </tr> <tr valign="middle"> <td colspan="1" rowspan="1" align="left">4.2.0</td> <td colspan="1" rowspan="1" align="left"> <b><tt>EXTR_IF_EXISTS</tt></b> and <b><tt>EXTR_PREFIX_IF_EXISTS</tt></b> were added. </td> </tr> <tr valign="middle"> <td colspan="1" rowspan="1" align="left">4.0.5</td> <td colspan="1" rowspan="1" align="left"> This function now returns the number of variables extracted. <b><tt>EXTR_PREFIX_INVALID</tt></b> was added. <b><tt>EXTR_PREFIX_ALL</tt></b> includes numeric variables as well. </td> </tr> </tbody> </colgroup> </table> </p> </div> <div class="refsect1 examples"> <h3 class="title">Examples</h3> <p class="para"> <div class="example"> <p><b>Example #1 <b>extract()</b> example</b></p> <div class="example-contents"><p> A possible use for <b>extract()</b> is to import into the symbol table variables contained in an associative array returned by <a href="function.wddx-deserialize.html" class="function">wddx_deserialize()</a>. </p></div> <div class="example-contents"><div class="phpcode"><code><span style="color: #000000"><span style="color: #0000BB"><?php<br /><br /></span><span style="color: #FF8000">/* Suppose that $var_array is an array returned from<br /> wddx_deserialize */<br /><br /></span><span style="color: #0000BB">$size </span><span style="color: #007700">= </span><span style="color: #DD0000">"large"</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$var_array </span><span style="color: #007700">= array(</span><span style="color: #DD0000">"color" </span><span style="color: #007700">=> </span><span style="color: #DD0000">"blue"</span><span style="color: #007700">,<br /> </span><span style="color: #DD0000">"size" </span><span style="color: #007700">=> </span><span style="color: #DD0000">"medium"</span><span style="color: #007700">,<br /> </span><span style="color: #DD0000">"shape" </span><span style="color: #007700">=> </span><span style="color: #DD0000">"sphere"</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">extract</span><span style="color: #007700">(</span><span style="color: #0000BB">$var_array</span><span style="color: #007700">, </span><span style="color: #0000BB">EXTR_PREFIX_SAME</span><span style="color: #007700">, </span><span style="color: #DD0000">"wddx"</span><span style="color: #007700">);<br /><br />echo </span><span style="color: #DD0000">"$color, $size, $shape, $wddx_size\n"</span><span style="color: #007700">;<br /><br /></span><span style="color: #0000BB">?></span></span></code></div> </div> <div class="example-contents"><p>The above example will output:</p></div> <div class="example-contents"><pre><div class="cdata"><pre>blue, large, sphere, medium</pre></div> </pre></div> <div class="example-contents"><p> The <var class="varname">$size</var> wasn't overwritten, because we specified <b><tt>EXTR_PREFIX_SAME</tt></b>, which resulted in <var class="varname">$wddx_size</var> being created. If <b><tt>EXTR_SKIP</tt></b> was specified, then $wddx_size wouldn't even have been created. <b><tt>EXTR_OVERWRITE</tt></b> would have caused <var class="varname">$size</var> to have value "medium", and <b><tt>EXTR_PREFIX_ALL</tt></b> would result in new variables being named <var class="varname">$wddx_color</var>, <var class="varname">$wddx_size</var>, and <var class="varname">$wddx_shape</var>. </p></div> </div> </p> </div> <div class="refsect1 notes"> <h3 class="title">Notes</h3> <div class="warning"><b class="warning">Warning</b> <p class="para"> Do not use <b>extract()</b> on untrusted data, like user-input (<var class="varname"><a href="reserved.variables.get.html" class="classname">$_GET</a></var>, ...). If you do, for example, if you want to run old code that relies on <a href="security.globals.html" class="link">register_globals</a> temporarily, make sure you use one of the non-overwriting <i><tt class="parameter">extract_type</tt></i> values such as <b><tt>EXTR_SKIP</tt></b> and be aware that you should extract in the same order that's defined in <a href="ini.core.html#ini.variables-order" class="link">variables_order</a> within the <a href="ini.html" class="link"><var class="filename">php.ini</var></a>. </p> </div> </div> <div class="refsect1 seealso"> <h3 class="title">See Also</h3> <p class="para"> <ul class="simplelist"> <li class="member"><a href="function.compact.html" class="function" rel="rdfs-seeAlso">compact()</a></li> </ul> </p> </div></div><hr /><div style="text-align: center;"> <div class="prev" style="text-align: left; float: left;"><a href="function.end.html">end</a></div> <div class="next" style="text-align: right; float: right;"><a href="function.in-array.html">in_array</a></div> <div class="up"><a href="ref.array.html">Array 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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