gistfile1.php

static function getRandomIndices($upto, $howmany) {
	$max = $upto - 1;
	$candidates = range(0, $max); 
	if ($howmany >= $upto) {
		return $candidates;
	}
	
	$indices = array();
	for ($i = 0; $i < $howmany; $i++) {
		$idx = rand($i, $max);
		$indices[] = $candidates[$idx];
		$candidates[$idx] = $candidates[$i];
	}
	return $indices;
}