WeberTrivia.com -> PHP Manual -> http_build

Description

string http_build_query ( array formdata [, string numeric_prefix])

Generates a URL-encoded query string from the associative (or indexed) array provided. formdata may be an array or object containing properties. A formdata array may be a simple one-dimensional structure, or an array of arrays (who in turn may contain other arrays). If numeric indices are used in the base array and a numeric_prefix is provided, it will be prepended to the numeric index for elements in the base array only. This is to allow for legal variable names when the data is decoded by PHP or another CGI application later on.

Example 1. Simple usage of http_build_query()

 <?php
$data = array('foo'=>'bar',
              'baz'=>'boom',
              'cow'=>'milk',
              'php'=>'hypertext processor');
              
echo http_build_query($data); // foo=bar&baz=boom&cow=milk&php=hypertext+processor
?>

Example 2. http_build_query() with numerically index elements.

 <?php
$data = array('foo', 'bar', 'baz', 'boom', 'cow' => 'milk', 'php' =>'hypertext processor');
              
echo http_build_query($data);
/* Outputs:
      0=foo&1=bar&2=baz&3=boom&cow=milk&php=hypertext+processor
 */
 
echo http_build_query($data, 'myvar_');
/* Outputs:
      myvar_0=foo&myvar_1=bar&myvar_2=baz&myvar_3=boom&cow=milk&php=hypertext+processor
 */
?>

Example 3. http_build_query() with complex arrays

 <?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_');
?>

this will output : (word wrapped for readability)

user[name]=Bob+Smith&user[age]=47&user[sex]=M&user[dob]=5%1F12%1F1956& pastimes[0]=golf&pastimes[1]=opera&pastimes[2]=poker&pastimes[3]=rap& children[bobby][age]=12&children[bobby][sex]=M&children[sally][age]=8& children[sally][sex]=F&flags_0=CEO

Note: 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.

Example 4. Using http_build_query() with an object

 <?php
class myClass {
  var $foo;
  var $baz;
  
  function myClass() 
  {
    $this->foo = 'bar';
    $this->baz = 'boom';
  }
}

$data = new myClass();

echo http_build_query($data); // foo=bar&baz=boom

?>