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URL Functions
PHP Manual

# http_build_query

Generate URL-encoded query string

### Description

string http_build_query ( mixed `$query_data` [, string `$numeric_prefix` [, string `$arg_separator` [, int `$enc_type` = `PHP_QUERY_RFC1738` ]]] )

Generates a URL-encoded query string from the associative (or indexed) array provided.

### Parameters

`query_data`

  May be an array or object containing properties.

  If `query_data` is an array, it may be a simple one-dimensional structure, or an array of arrays (which in turn may contain other arrays).

  If `query_data` is an object, then only public properties will be incorporated into the result.

`numeric_prefix`

  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.

  This is meant to allow for legal variable names when the data is decoded by PHP or another CGI application later on.

`arg_separator`

  arg_separator.output is used to separate arguments, unless this parameter is specified, and is then used.

`enc_type`

  By default, `PHP_QUERY_RFC1738`.

  If `enc_type` is `PHP_QUERY_RFC1738`, then encoding is performed per » RFC 1738 and the application/x-www-form-urlencoded media type, which implies that spaces are encoded as plus (+) signs.

  If `enc_type` is `PHP_QUERY_RFC3986`, then encoding is performed according to » RFC 3986, and spaces will be percent encoded (%20).

### Return Values

Returns a URL-encoded string.

### Changelog

Version | Description
--- | ---
5.4.0 | The `enc_type` parameter was added.
5.1.3 | Square brackets are escaped.
5.1.2 | The `arg_separator` parameter was added.

### Examples

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

The above example will output:

    foo=bar&baz=boom&cow=milk&php=hypertext+processor
    foo=bar&amp;baz=boom&amp;cow=milk&amp;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) . "\n";
echo http_build_query($data, 'myvar_');
?>`

The above example will output:

    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

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%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

> 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 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);
?>`

The above example will output:

    pub=publicParent&pub_bar%5Bpub%5D=publicChild

### See Also

- parse_str
- parse_url
- urlencode
- array_walk