mirror of
https://github.com/sigmasternchen/php-doc-en
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260 lines
8.7 KiB
XML
260 lines
8.7 KiB
XML
<?xml version="1.0" encoding="utf-8"?>
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<!-- $Revision$ -->
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<refentry xml:id="function.extract" xmlns="http://docbook.org/ns/docbook">
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<refnamediv>
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<refname>extract</refname>
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<refpurpose>Import variables into the current symbol table from an array</refpurpose>
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</refnamediv>
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<refsect1 role="description">
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&reftitle.description;
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<methodsynopsis>
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<type>int</type><methodname>extract</methodname>
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<methodparam><type>array</type><parameter role="reference">array</parameter></methodparam>
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<methodparam choice="opt"><type>int</type><parameter>flags</parameter><initializer><constant>EXTR_OVERWRITE</constant></initializer></methodparam>
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<methodparam choice="opt"><type>string</type><parameter>prefix</parameter><initializer>""</initializer></methodparam>
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</methodsynopsis>
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<para>
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Import variables from an array into the current symbol table.
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</para>
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<para>
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Checks each key to see whether it has a valid variable name.
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It also checks for collisions with existing variables in
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the symbol table.
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</para>
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<warning>
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<para>
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Do not use <function>extract</function> on untrusted data, like user input
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(e.g. <varname>$_GET</varname>, <varname>$_FILES</varname>).
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</para>
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</warning>
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</refsect1>
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<refsect1 role="parameters">
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&reftitle.parameters;
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<para>
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<variablelist>
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<varlistentry>
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<term><parameter>array</parameter></term>
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<listitem>
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<para>
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An associative array. This function treats keys as variable names and
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values as variable values. For each key/value pair it will create a
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variable in the current symbol table, subject to
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<parameter>flags</parameter> and <parameter>prefix</parameter> parameters.
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</para>
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<para>
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You must use an associative array; a numerically indexed array
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will not produce results unless you use <constant>EXTR_PREFIX_ALL</constant> or
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<constant>EXTR_PREFIX_INVALID</constant>.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>flags</parameter></term>
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<listitem>
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<para>
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The way invalid/numeric keys and collisions are treated is determined
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by the extraction <parameter>flags</parameter>. It can be one of the
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following values:
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<variablelist>
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<varlistentry>
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<term><constant>EXTR_OVERWRITE</constant></term>
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<listitem>
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<simpara>
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If there is a collision, overwrite the existing variable.
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</simpara>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>EXTR_SKIP</constant></term>
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<listitem>
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<simpara>
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If there is a collision, don't overwrite the existing
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variable.
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</simpara>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>EXTR_PREFIX_SAME</constant></term>
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<listitem>
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<simpara>If there is a collision, prefix the variable name with
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<parameter>prefix</parameter>.
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</simpara>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>EXTR_PREFIX_ALL</constant></term>
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<listitem>
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<simpara>
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Prefix all variable names with
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<parameter>prefix</parameter>.
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</simpara>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>EXTR_PREFIX_INVALID</constant></term>
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<listitem>
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<simpara>
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Only prefix invalid/numeric variable names with
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<parameter>prefix</parameter>.
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</simpara>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>EXTR_IF_EXISTS</constant></term>
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<listitem>
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<simpara>
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Only overwrite the variable if it already exists in the
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current symbol table, otherwise do nothing. This is useful
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for defining a list of valid variables and then extracting
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only those variables you have defined out of
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<varname>$_REQUEST</varname>, for example.
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</simpara>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>EXTR_PREFIX_IF_EXISTS</constant></term>
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<listitem>
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<simpara>
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Only create prefixed variable names if the non-prefixed version
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of the same variable exists in the current symbol table.
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</simpara>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><constant>EXTR_REFS</constant></term>
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<listitem>
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<simpara>
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Extracts variables as references. This effectively means that the
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values of the imported variables are still referencing the values of
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the <parameter>array</parameter> parameter. You can use this flag
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on its own or combine it with any other flag by OR'ing the
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<parameter>flags</parameter>.
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</simpara>
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</listitem>
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</varlistentry>
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</variablelist>
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</para>
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<para>
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If <parameter>flags</parameter> is not specified, it is
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assumed to be <constant>EXTR_OVERWRITE</constant>.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>prefix</parameter></term>
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<listitem>
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<para>
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Note that <parameter>prefix</parameter> is only required if
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<parameter>flags</parameter> is <constant>EXTR_PREFIX_SAME</constant>,
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<constant>EXTR_PREFIX_ALL</constant>, <constant>EXTR_PREFIX_INVALID</constant>
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or <constant>EXTR_PREFIX_IF_EXISTS</constant>. If
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the prefixed result is not a valid variable name, it is not
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imported into the symbol table. Prefixes are automatically separated from
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the array key by an underscore character.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</para>
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</refsect1>
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<refsect1 role="returnvalues">
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&reftitle.returnvalues;
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<para>
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Returns the number of variables successfully imported into the symbol
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table.
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</para>
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</refsect1>
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<refsect1 role="examples">
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&reftitle.examples;
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<para>
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<example>
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<title><function>extract</function> example</title>
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<para>
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A possible use for <function>extract</function> is to import into the
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symbol table variables contained in an associative array returned by
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<function>wddx_deserialize</function>.
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</para>
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<programlisting role="php">
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<![CDATA[
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<?php
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/* Suppose that $var_array is an array returned from
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wddx_deserialize */
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$size = "large";
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$var_array = array("color" => "blue",
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"size" => "medium",
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"shape" => "sphere");
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extract($var_array, EXTR_PREFIX_SAME, "wddx");
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echo "$color, $size, $shape, $wddx_size\n";
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?>
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]]>
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</programlisting>
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&example.outputs;
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<screen>
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<![CDATA[
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blue, large, sphere, medium
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]]>
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</screen>
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<para>
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The <varname>$size</varname> wasn't overwritten because we specified
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<constant>EXTR_PREFIX_SAME</constant>, which resulted in
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<varname>$wddx_size</varname> being created. If <constant>EXTR_SKIP</constant> was
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specified, then <varname>$wddx_size</varname> wouldn't even have been created.
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<constant>EXTR_OVERWRITE</constant> would have caused <varname>$size</varname> to have
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value "medium", and <constant>EXTR_PREFIX_ALL</constant> would result in new variables
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being named <varname>$wddx_color</varname>,
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<varname>$wddx_size</varname>, and
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<varname>$wddx_shape</varname>.
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</para>
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</example>
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</para>
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</refsect1>
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<refsect1 role="notes">
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&reftitle.notes;
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<warning>
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<para>
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Do not use <function>extract</function> on untrusted data, like
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user input
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(i.e. <varname>$_GET</varname>, <varname>$_FILES</varname>, etc.).
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If you do, make sure you use one of the non-overwriting
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<parameter>flags</parameter> values such as
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<constant>EXTR_SKIP</constant> and be aware that you should extract
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in the same order that's defined in
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<link linkend="ini.variables-order">variables_order</link> within the
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<link linkend="ini">&php.ini;</link>.
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</para>
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</warning>
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</refsect1>
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<refsect1 role="seealso">
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&reftitle.seealso;
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<para>
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<simplelist>
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<member><function>compact</function></member>
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<member><function>list</function></member>
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</simplelist>
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</para>
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</refsect1>
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</refentry>
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<!-- Keep this comment at the end of the file
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Local variables:
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mode: sgml
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sgml-omittag:t
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sgml-shorttag:t
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sgml-minimize-attributes:nil
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sgml-always-quote-attributes:t
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sgml-indent-step:1
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sgml-indent-data:t
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indent-tabs-mode:nil
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sgml-parent-document:nil
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sgml-default-dtd-file:"~/.phpdoc/manual.ced"
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sgml-exposed-tags:nil
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sgml-local-catalogs:nil
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sgml-local-ecat-files:nil
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End:
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vim600: syn=xml fen fdm=syntax fdl=2 si
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vim: et tw=78 syn=sgml
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vi: ts=1 sw=1
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-->
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