FUNCTION permutations($letters,$num){ 
    $last = STR_REPEAT($letters{0},$num); 
    $result = ARRAY(); 
    WHILE($last != STR_REPEAT(lastchar($letters),$num)){ 
        $result[] = $last; 
        $last = char_add($letters,$last,$num-1); 
    } 
    $result[] = $last; 
    RETURN $result; 
} 
FUNCTION char_add($digits,$string,$char){ 
    IF($string{$char} <> lastchar($digits)){ 
        $string{$char} = $digits{STRPOS($digits,$string{$char})+1}; 
        RETURN $string; 
    }ELSE{ 
        $string = changeall($string,$digits{0},$char); 
        RETURN char_add($digits,$string,$char-1); 
    } 
} 
FUNCTION lastchar($string){ 
    RETURN $string{STRLEN($string)-1}; 
} 
FUNCTION changeall($string,$char,$start = 0,$end = 0){ 
    IF($end == 0) $end = STRLEN($string)-1; 
    FOR($i=$start;$i<=$end;$i++){ 
        $string{$i} = $char; 
    } 
    RETURN $string; 
} 

// cara pakai
$Array=permutations("12345",2); 
echo implode(',',$Array);