how to serialize array as url queryString in php?

Question

I need to convert an array such as this:

$arr = array(1, 2, 3) ; 

to this format:

arr[0]=1&arr[1]=2&arr[2]=3

is there any built in function in php or i must create this my self?

Answer 1

expected output should require key name in input data array, see below and after that use http_build_query() function to created query string

<?php 
$arr = array("arr" => array(1, 2, 3)) ; 
echo http_build_query($arr);
?>

encode output default

arr%5B0%5D=1&arr%5B1%5D=2&arr%5B2%5D=3

and if you need decode output then

<?php 
$arr = array("arr" => array(1, 2, 3)) ; 
echo urldecode(http_build_query($arr));
?>

arr[0]=1&arr[1]=2&arr[2]=3