- parse_str: documentation ( source)
- var_export: documentation ( source)
- preg_replace: documentation ( source)
<?php
$string = 'key1\value1\key2\value2\key3\value3\key4\value4\key5\value5';
parse_str(preg_replace('/([^\\\\]+)\\\\([^\\\\]+)\\\\?/', '$1=$2&', $string), $output);
var_export($output);