count.xml

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<!-- $Revision$ -->

<refentry xml:id="function.count" xmlns="http://docbook.org/ns/docbook">
 <refnamediv>
  <refname>count</refname>
  <refpurpose>Counts all elements in an array or in a <interfacename>Countable</interfacename> object</refpurpose>
 </refnamediv>

 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type>int</type><methodname>count</methodname>
   <methodparam><type class="union"><type>Countable</type><type>array</type></type><parameter>value</parameter></methodparam>
   <methodparam choice="opt"><type>int</type><parameter>mode</parameter><initializer><constant>COUNT_NORMAL</constant></initializer></methodparam>
  </methodsynopsis>
  <para>
   Counts all elements in an array when used with an array. When used with an
   object that implements the <interfacename>Countable</interfacename> interface, it returns
   the return value of the method <methodname>Countable::count</methodname>.
  </para>
 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    <varlistentry>
     <term><parameter>value</parameter></term>
     <listitem>
      <para>
       An array or <interfacename>Countable</interfacename> object.
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>mode</parameter></term>
     <listitem>
      <para>
       If the optional <parameter>mode</parameter> parameter is set to
       <constant>COUNT_RECURSIVE</constant> (or 1), <function>count</function>
       will recursively count the array.  This is particularly useful for
       counting all the elements of a multidimensional array.
      </para>
      <caution>
       <para>
        <function>count</function> can detect recursion to avoid an infinite
        loop, but will emit an <constant>E_WARNING</constant> every time it
        does (in case the array contains itself more than once) and return a
        count higher than may be expected.
       </para>
      </caution>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
 </refsect1>

 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   Returns the number of elements in <parameter>value</parameter>.
   Prior to PHP 8.0.0, if the parameter was neither an &array; nor an &object; that
   implements the <interfacename>Countable</interfacename> interface,
   <literal>1</literal> would be returned,
   unless <parameter>value</parameter> was &null;, in which case
   <literal>0</literal> would be returned.
  </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>
       <function>count</function> will now throw <classname>TypeError</classname> on 
       invalid countable types passed to the <parameter>value</parameter> parameter.
      </entry>
     </row>
     <row>
      <entry>7.2.0</entry>
      <entry>
       <function>count</function> will now yield a warning on invalid countable types 
       passed to the <parameter>value</parameter> parameter.
      </entry>
     </row>
    </tbody>
   </tgroup>
  </informaltable>
 </refsect1>

 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example xml:id="count.example.basic">
    <title><function>count</function> example</title>
    <programlisting role="php">
<![CDATA[
<?php
$a[0] = 1;
$a[1] = 3;
$a[2] = 5;
var_dump(count($a));

$b[0]  = 7;
$b[5]  = 9;
$b[10] = 11;
var_dump(count($b));
?>
]]>
    </programlisting>
    &example.outputs;
    <screen role="php">
<![CDATA[
int(3)
int(3)
]]>
    </screen>
   </example>
  </para>
  <para>
   <example xml:id="count.example.badexample">
    <title><function>count</function> non Countable|array example (bad example - don't do this)</title>
    <programlisting role="php">
<![CDATA[
<?php
$b[0]  = 7;
$b[5]  = 9;
$b[10] = 11;
var_dump(count($b));

var_dump(count(null));

var_dump(count(false));
?>
]]>
    </programlisting>
    &example.outputs;
    <screen role="php">
<![CDATA[
int(3)
int(0)
int(1)
]]>
    </screen>
    &example.outputs.72;
    <screen role="php">
<![CDATA[
int(3)

Warning: count(): Parameter must be an array or an object that implements Countable in … on line 12
int(0)

Warning: count(): Parameter must be an array or an object that implements Countable in … on line 14
int(1)
]]>
    </screen>
    &example.outputs.8;
    <screen role="php">
<![CDATA[
int(3)

Fatal error: Uncaught TypeError: count(): Argument #1 ($var) must be of type Countable .. on line 12
]]>
    </screen>
   </example>
  </para>
  <para>
   <example xml:id="count.example.recursive">
    <title>Recursive <function>count</function> example</title>
    <programlisting role="php">
<![CDATA[
<?php
$food = array('fruits' => array('orange', 'banana', 'apple'),
              'veggie' => array('carrot', 'collard', 'pea'));

// recursive count
var_dump(count($food, COUNT_RECURSIVE));

// normal count
var_dump(count($food));

?>
]]>
    </programlisting>
    &example.outputs;
    <screen role="php">
<![CDATA[
int(8)
int(2)
]]>
    </screen>
   </example>
  </para>
  <para>
   <example xml:id="count.example.countable">
    <title><interfacename>Countable</interfacename> object</title>
    <programlisting role="php">
<![CDATA[
<?php
class CountOfMethods implements Countable
{
    private function someMethod()
    {
    }

    public function count(): int
    {
        return count(get_class_methods($this));
    }
}

$obj = new CountOfMethods();
var_dump(count($obj));
?>
]]>
    </programlisting>
    &example.outputs;
    <screen role="php">
<![CDATA[
int(2)
]]>
    </screen>
   </example>
  </para>
 </refsect1>

 <refsect1 role="seealso">
  &reftitle.seealso;
  <para>
   <simplelist>
    <member><function>is_array</function></member>
    <member><function>isset</function></member>
    <member><function>empty</function></member>
    <member><function>strlen</function></member>
    <member><function>is_countable</function></member>
    <member><link linkend="language.types.array">Arrays</link></member>
   </simplelist>
  </para>
 </refsect1>

</refentry>

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