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

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

/*
foo=bar&baz=boom&cow=milk&php=hypertext+processor
foo=bar&amp;baz=boom&amp;cow=milk&amp;php=hypertext+processor
*/