php-doc-en/reference/var/functions/print-r.xml

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<!-- $Revision$ -->
<refentry xml:id="function.print-r" xmlns="http://docbook.org/ns/docbook">
 <refnamediv>
  <refname>print_r</refname>
  <refpurpose>
   Prints human-readable information about a variable
  </refpurpose>
 </refnamediv>
 
 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type>mixed</type><methodname>print_r</methodname>
   <methodparam><type>mixed</type><parameter>expression</parameter></methodparam>
   <methodparam choice="opt"><type>bool</type><parameter>return</parameter><initializer>false</initializer></methodparam>
  </methodsynopsis>
  <para>
   <function>print_r</function> displays information about a variable
   in a way that's readable by humans.  
  </para>
  <para>
   <function>print_r</function>, <function>var_dump</function> and
   <function>var_export</function> will
   also show protected and private properties of objects with PHP 5.
   Static class members will not be shown.
  </para>
 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    <varlistentry>
     <term><parameter>expression</parameter></term>
     <listitem>
      <para>
       The expression to be printed.
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>return</parameter></term>
     <listitem>
      <para>
       If you would like to capture the output of <function>print_r</function>, 
       use the <parameter>return</parameter> parameter.  When this parameter is set
       to &true;, <function>print_r</function> will return the information rather than print it.
      </para>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
 </refsect1>

 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   If given a <type>string</type>, <type>integer</type> or <type>float</type>,
   the value itself will be printed.  If given an <type>array</type>, values
   will be presented in a format that shows keys and elements.  Similar
   notation is used for <type>object</type>s.
  </para>
  <para>
   When the <parameter>return</parameter> parameter is &true;, this function
   will return a <type>string</type>. Otherwise, the return value is &true;.
  </para>
 </refsect1>

 <refsect1 role="notes">
  &reftitle.notes;
  &note.uses-ob;
 </refsect1>

 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example>
    <title><function>print_r</function> example</title>
    <programlisting role="php">
<![CDATA[
<pre>
<?php
$a = array ('a' => 'apple', 'b' => 'banana', 'c' => array ('x', 'y', 'z'));
print_r ($a);
?>
</pre>
]]>
    </programlisting>
    &example.outputs;
    <screen>
<![CDATA[
<pre>
Array
(
    [a] => apple
    [b] => banana
    [c] => Array
        (
            [0] => x
            [1] => y
            [2] => z
        )
)
</pre>
]]>
    </screen>
   </example>
  </para>
  <para>
   <example>
    <title><parameter>return</parameter> parameter example</title>
    <programlisting role="php">
<![CDATA[
<?php
$b = array ('m' => 'monkey', 'foo' => 'bar', 'x' => array ('x', 'y', 'z'));
$results = print_r($b, true); // $results now contains output from print_r
?>
]]>
    </programlisting>
   </example>
  </para>
 </refsect1>

 <refsect1 role="seealso">
  &reftitle.seealso;
  <para>
   <simplelist>
    <member><function>ob_start</function></member>
    <member><function>var_dump</function></member>
    <member><function>var_export</function></member>
   </simplelist>
  </para>
 </refsect1>

</refentry>

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