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<refentry xmlns="http://docbook.org/ns/docbook" xml:id="function.session-unset">
 <refnamediv>
  <refname>session_unset</refname>
  <refpurpose>Free all session variables</refpurpose>
 </refnamediv>
 
 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type>bool</type><methodname>session_unset</methodname>
   <void/>
  </methodsynopsis>
  <para>
   The <function>session_unset</function> function frees all session variables
   currently registered.
  </para>
 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  &no.function.parameters;
 </refsect1>

 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   &return.success;
  </para>
 </refsect1>

 <refsect1 role="changelog">
  &reftitle.changelog;
  <informaltable>
   <tgroup cols="2">
    <thead>
     <row>
      <entry>&Version;</entry>
      <entry>&Description;</entry>
     </row>
    </thead>
    <tbody>
     <row>
      <entry>7.2.0</entry>
      <entry>
       The return type of this function is <type>bool</type> now.
       Formerly, it has been <type>void</type>.
      </entry>
     </row>
    </tbody>
   </tgroup>
  </informaltable>
 </refsect1>

 <refsect1 role="notes">
  &reftitle.notes;
  <note>
   <para>
    If <varname>$_SESSION</varname> is used, use <function>unset</function> to
    unregister a session variable, i.e.
    <code>unset($_SESSION['varname']);</code>.
   </para>
  </note>
  <caution>
   <para>
    Do NOT unset the whole <varname>$_SESSION</varname> with
    <code>unset($_SESSION)</code> as this will disable the registering
    of session variables through the <varname>$_SESSION</varname> superglobal.
   </para>
  </caution>
  <note>
   <para>
    The use of <function>session_unset</function> is identical to <code>$_SESSION = []</code>.
   </para>
  </note>
  <caution>
   <para>
    This function works only if a session is active. It will not clear the
    <varname>$_SESSION</varname> array if the session has not been started yet
    or has already been destroyed. Use <code>$_SESSION = []</code> to unset all
    session variables even if the session is not active.
   </para>
  </caution>
 </refsect1>

</refentry>

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