archived-doc-en/reference/array/functions/compact.xml

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<refentry xml:id="function.compact" xmlns="http://docbook.org/ns/docbook">
 <refnamediv>
  <refname>compact</refname>
  <refpurpose>Create array containing variables and their values</refpurpose>
 </refnamediv>
 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type>array</type><methodname>compact</methodname>
   <methodparam><type class="union"><type>array</type><type>string</type></type><parameter>var_name</parameter></methodparam>
   <methodparam rep="repeat"><type class="union"><type>array</type><type>string</type></type><parameter>var_names</parameter></methodparam>
  </methodsynopsis>
  <para>
   Creates an array containing variables and their values.
  </para>
  <para>
   For each of these, <function>compact</function> looks for a
   variable with that name in the current
   <link linkend="features.gc.refcounting-basics">symbol table</link>
   and adds it to the output array such that the variable name becomes the key
   and the contents of the variable become the value for that key.
   In short, it does the opposite of <function>extract</function>.
  </para>
  <note>
   <para>
    Before PHP 7.3, any strings that are not set will silently be skipped.
   </para>
  </note> 
 </refsect1>
 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    <varlistentry>
     <term><parameter>var_name</parameter></term>
     <term><parameter>var_names</parameter></term>
     <listitem>
      <para>
       <function>compact</function> takes a variable number of parameters.
       Each parameter can be either a string containing the name of the
       variable, or an array of variable names.  The array can contain other
       arrays of variable names inside it; <function>compact</function>
       handles it recursively.
      </para>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
 </refsect1>
 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   Returns the output array with all the variables added to it.
  </para>
 </refsect1>

 <refsect1 role="errors">
  &reftitle.errors;
  <para>
   <function>compact</function> issues an <constant>E_WARNING</constant> level error if a given string
   refers to an unset variable.
  </para>
 </refsect1>

 <refsect1 role="changelog"><!-- {{{ -->
  &reftitle.changelog;
  <informaltable>
   <tgroup cols="2">
    <thead>
     <row>
      <entry>&Version;</entry>
      <entry>&Description;</entry>
     </row>
    </thead>
    <tbody>
     <row>
      <entry>8.0.0</entry>
      <entry>
       If a given string references an unset variable, an <constant>E_WARNING</constant> level error is now issued.
      </entry>
     </row>
     <row>
      <entry>7.3.0</entry>
      <entry>
       <function>compact</function> now issues an <constant>E_NOTICE</constant> level error if a given string
       refers to an unset variable. Formerly, such strings have been silently skipped.
      </entry>
     </row>
    </tbody>
   </tgroup>
  </informaltable>
 </refsect1><!-- }}} -->

 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example>
    <title><function>compact</function> example</title>
    <programlisting role="php">
<![CDATA[
<?php

$city  = "San Francisco";
$state = "CA";
$event = "SIGGRAPH";

$location_vars = array("city", "state");

$result = compact("event", $location_vars);
print_r($result);

?>
]]>
    </programlisting>
    &example.outputs;
    <screen role="php">
<![CDATA[
Array
(
    [event] => SIGGRAPH
    [city] => San Francisco
    [state] => CA
)
]]>
    </screen>
   </example>
  </para>
 </refsect1>
 <refsect1 role="notes">
  &reftitle.notes;
  <note>
   <title>Gotcha</title>
   <para>
    Because <link linkend="language.variables.variable">variable
    variables</link> may not be used with PHP's
    <link linkend="language.variables.superglobals">Superglobal
    arrays</link> within functions, the Superglobal arrays may not be passed
    into <function>compact</function>.
   </para>
  </note>
 </refsect1>
 <refsect1 role="seealso">
  &reftitle.seealso;
  <para>
   <simplelist>
    <member><function>extract</function></member>
   </simplelist>
  </para>
 </refsect1>
</refentry>
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