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<refentry xmlns="http://docbook.org/ns/docbook" xml:id="function.count-chars">
 <refnamediv>
  <refname>count_chars</refname>
  <refpurpose>Return information about characters used in a string</refpurpose>
 </refnamediv>
 
 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type>mixed</type><methodname>count_chars</methodname>
   <methodparam><type>string</type><parameter>string</parameter></methodparam>
   <methodparam choice="opt"><type>int</type><parameter>mode</parameter><initializer>0</initializer></methodparam>
  </methodsynopsis>
  <para>
   Counts the number of occurrences of every byte-value (0..255) in
   <parameter>string</parameter> and returns it in various ways.
  </para>
 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    <varlistentry>
     <term><parameter>string</parameter></term>
     <listitem>
      <para>
       The examined string.
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>mode</parameter></term>
     <listitem>
      <para>
       See return values.
      </para>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
 </refsect1>

 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   Depending on <parameter>mode</parameter>
   <function>count_chars</function> returns one of the following:
   <itemizedlist>
    <listitem>
     <simpara>
      0 - an array with the byte-value as key and the frequency of
      every byte as value.
     </simpara>
    </listitem>
    <listitem>
     <simpara>
      1 - same as 0 but only byte-values with a frequency greater
      than zero are listed.
     </simpara>
    </listitem>
    <listitem>
     <simpara>
      2 - same as 0 but only byte-values with a frequency equal to
      zero are listed.
     </simpara>
    </listitem>
    <listitem>
     <simpara>
      3 - a string containing all unique characters is returned.
     </simpara>
    </listitem>
    <listitem>
     <simpara>
      4 - a string containing all not used characters is returned.
     </simpara>
    </listitem>
   </itemizedlist>
  </para>
 </refsect1>

 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example>
    <title><function>count_chars</function> example</title>
    <programlisting role="php">
<![CDATA[
<?php
$data = "Two Ts and one F.";

foreach (count_chars($data, 1) as $i => $val) {
   echo "There were $val instance(s) of \"" , chr($i) , "\" in the string.\n";
}
?>
]]>
    </programlisting>
    &example.outputs;
    <screen>
<![CDATA[
There were 4 instance(s) of " " in the string.
There were 1 instance(s) of "." in the string.
There were 1 instance(s) of "F" in the string.
There were 2 instance(s) of "T" in the string.
There were 1 instance(s) of "a" in the string.
There were 1 instance(s) of "d" in the string.
There were 1 instance(s) of "e" in the string.
There were 2 instance(s) of "n" in the string.
There were 2 instance(s) of "o" in the string.
There were 1 instance(s) of "s" in the string.
There were 1 instance(s) of "w" in the string.
]]>
    </screen>
   </example>
  </para>
 </refsect1>

 <refsect1 role="seealso">
  &reftitle.seealso;
  <para>
   <simplelist>
    <member><function>strpos</function></member>
    <member><function>substr_count</function></member>
   </simplelist>
  </para>
 </refsect1>

</refentry>

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