PHP http_build_query Function: Usage, Parameters, and Examples

The http_build_query function in PHP creates a URL‑encoded query string from a given array or object, which can then be appended to a URL for HTTP requests.

Parameters :

query_data – an array or object (public properties only) that provides the data to be encoded. It may be a simple one‑dimensional array or a nested array structure.

numeric_prefix – a string prefixed to numeric indices when the base array contains numeric keys, ensuring valid variable names after decoding.

arg_separator – the separator used between arguments; defaults to the value of arg_separator.output if not supplied.

enc_type – encoding type, default PHP_QUERY_RFC1738 (spaces become "+"), or PHP_QUERY_RFC3986 (spaces become "%20").

Return value : a URL‑encoded string representing the supplied data.

Example 1 – basic usage:

'bar',
    'baz' => 'boom',
    'cow' => 'milk',
    'php' => 'hypertext processor'
);

echo http_build_query($data) . "\n";
?>

Output:

foo=bar&baz=boom&cow=milk&php=hypertext+processor

Example 2 – using a numeric prefix:

'milk', 'php' => 'hypertext processor');

echo http_build_query($data, 'myvar_') . "\n";
?>

Output:

myvar_0=foo&myvar_1=bar&myvar_2=baz&myvar_3=boom&cow=milk&php=hypertext+processor

These examples demonstrate how http_build_query can be customized with different separators and prefixes to produce query strings suitable for various web applications.