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<refentry xml:id="function.http-build-query" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink">
 <refnamediv>
  <refname>http_build_query</refname>
  <refpurpose>Generate URL-encoded query string</refpurpose>
 </refnamediv>

 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type>string</type><methodname>http_build_query</methodname>
   <methodparam><type>mixed</type><parameter>query_data</parameter></methodparam>
   <methodparam choice="opt"><type>string</type><parameter>numeric_prefix</parameter></methodparam>
   <methodparam choice="opt"><type>string</type><parameter>arg_separator</parameter></methodparam>
   <methodparam choice="opt"><type>int</type><parameter>enc_type</parameter><initializer><constant>PHP_QUERY_RFC1738</constant></initializer></methodparam>
  </methodsynopsis>
  <para>
   Generates a URL-encoded query string from the associative (or indexed)
   array provided.
  </para>
 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    <varlistentry>
     <term><parameter>query_data</parameter></term>
     <listitem>
      <para>
       May be an array or object containing properties.
      </para>
      <para>
       If <parameter>query_data</parameter> is an array, it may be a simple
       one-dimensional structure, or an array of arrays (which in
       turn may contain other arrays).
      </para>
      <para>
       If <parameter>query_data</parameter> is an object, then only public
       properties will be incorporated into the result.
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>numeric_prefix</parameter></term>
     <listitem>
      <para>
       If numeric indices are used in the base array and this parameter is
       provided, it will be prepended to the numeric index for elements in
       the base array only.
      </para>
      <para>
       This is meant to allow for legal variable names when the data is
       decoded by PHP or another CGI application later on.
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>arg_separator</parameter></term>
     <listitem>
      <para>
       <link linkend="ini.arg-separator.output">arg_separator.output</link>
       is used to separate arguments, unless this parameter is specified,
       and is then used.
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>enc_type</parameter></term>
     <listitem>
      <para>&version.trunk.after.53;</para>
      <para>
       By default, <constant>PHP_QUERY_RFC1738</constant>.
      </para>
      <para>
       If <parameter>enc_type</parameter> is
       <constant>PHP_QUERY_RFC1738</constant>, then encoding is performed per
       <link xlink:href="&url.rfc;1738">RFC 1738</link> and the
       <literal>application/x-www-form-urlencoded</literal> media type, which
       implies that spaces are encoded as plus (<literal>+</literal>) signs.
      </para>
      <para>
       If <parameter>enc_type</parameter> is
       <constant>PHP_QUERY_RFC3986</constant>, then encoding is performed
       according to <link xlink:href="&url.rfc;3986">RFC 3986</link>, and
       spaces will be percent encoded (<literal>%20</literal>).
      </para>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
 </refsect1>

 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   Returns a URL-encoded string.
  </para>
 </refsect1>

 <refsect1 role="changelog">
  &reftitle.changelog;
  <para>
   <informaltable>
    <tgroup cols="2">
     <thead>
      <row>
       <entry>&Version;</entry>
       <entry>&Description;</entry>
      </row>
     </thead>
     <tbody>
      <row>
       <entry>&version.trunk.changelog;</entry>
       <entry>
        The <parameter>enc_type</parameter> parameter was added.
       </entry>
      </row>
      <row>
       <entry>5.1.3</entry>
       <entry>
        Square brackets are escaped.
       </entry>
      </row>
      <row>
       <entry>5.1.2</entry>
       <entry>
        The <parameter>arg_separator</parameter> parameter was added.
       </entry>
      </row>
     </tbody>
    </tgroup>
   </informaltable>
  </para>
 </refsect1>

 <refsect1 role="examples">
  &reftitle.examples;
  <example>
   <title>Simple usage of <function>http_build_query</function></title>
   <programlisting role="php">
<![CDATA[
<?php
$data = array('foo'=>'bar',
              'baz'=>'boom',
              'cow'=>'milk',
              'php'=>'hypertext processor');

echo http_build_query($data) . "\n";
echo http_build_query($data, '', '&amp;');

?>
]]>
   </programlisting>
   &example.outputs;
   <screen>
<![CDATA[
foo=bar&baz=boom&cow=milk&php=hypertext+processor
foo=bar&amp;baz=boom&amp;cow=milk&amp;php=hypertext+processor
]]>
   </screen>
  </example>

  <example>
   <title><function>http_build_query</function> with numerically index elements.</title>
   <programlisting role="php">
<![CDATA[
<?php
$data = array('foo', 'bar', 'baz', 'boom', 'cow' => 'milk', 'php' =>'hypertext processor');

echo http_build_query($data) . "\n";
echo http_build_query($data, 'myvar_');
?>
]]>
   </programlisting>
   &example.outputs;
   <screen>
<![CDATA[
0=foo&1=bar&2=baz&3=boom&cow=milk&php=hypertext+processor
myvar_0=foo&myvar_1=bar&myvar_2=baz&myvar_3=boom&cow=milk&php=hypertext+processor
]]>
   </screen>
  </example>
  <example>
   <title><function>http_build_query</function> with complex arrays</title>
   <programlisting role="php">
<![CDATA[
<?php
$data = array('user'=>array('name'=>'Bob Smith',
                            'age'=>47,
                            'sex'=>'M',
                            'dob'=>'5/12/1956'),
              'pastimes'=>array('golf', 'opera', 'poker', 'rap'),
              'children'=>array('bobby'=>array('age'=>12,
                                               'sex'=>'M'),
                                'sally'=>array('age'=>8,
                                               'sex'=>'F')),
              'CEO');

echo http_build_query($data, 'flags_');
?>
]]>
   </programlisting>
   <para>
    this will output : (word wrapped for readability)
   </para>
   <screen>
<![CDATA[
user%5Bname%5D=Bob+Smith&user%5Bage%5D=47&user%5Bsex%5D=M&
user%5Bdob%5D=5%2F12%2F1956&pastimes%5B0%5D=golf&pastimes%5B1%5D=opera&
pastimes%5B2%5D=poker&pastimes%5B3%5D=rap&children%5Bbobby%5D%5Bage%5D=12&
children%5Bbobby%5D%5Bsex%5D=M&children%5Bsally%5D%5Bage%5D=8&
children%5Bsally%5D%5Bsex%5D=F&flags_0=CEO
]]>
   </screen>
   <para>
    <note>
     <para>
      Only the numerically indexed element in the base array "CEO" received a
      prefix.  The other numeric indices, found under pastimes, do not
      require a string prefix to be legal variable names.
     </para>
    </note>
   </para>
  </example>

  <example>
   <title>Using <function>http_build_query</function> with an object</title>
   <programlisting role="php">
<![CDATA[
<?php
class parentClass {
    public    $pub      = 'publicParent';
    protected $prot     = 'protectedParent';
    private   $priv     = 'privateParent';
    public    $pub_bar  = Null;
    protected $prot_bar = Null;
    private   $priv_bar = Null;

    public function __construct(){
        $this->pub_bar  = new childClass();
        $this->prot_bar = new childClass();
        $this->priv_bar = new childClass();
    }
}

class childClass {
    public    $pub  = 'publicChild';
    protected $prot = 'protectedChild';
    private   $priv = 'privateChild';
}

$parent = new parentClass();

echo http_build_query($parent);
?>
]]>
   </programlisting>
   &example.outputs;
   <screen>
<![CDATA[
pub=publicParent&pub_bar%5Bpub%5D=publicChild
]]>
   </screen>
  </example>
 </refsect1>

 <refsect1 role="seealso">
  &reftitle.seealso;
  <para>
   <simplelist>
    <member><function>parse_str</function></member>
    <member><function>parse_url</function></member>
    <member><function>urlencode</function></member>
    <member><function>array_walk</function></member>
   </simplelist>
  </para>
 </refsect1>

</refentry>

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