action kalkulator

<?php

/*
ACT.PHP

ini skrip action kalkulator dengan 1 input.
*/

$i = 0;
$ask = null;
$return = null;

if (isset($_GET['ask'])) {
    $ask = $_GET['ask'];
    echo $ask . " = ";
}

function math($ask)
{

    $operator = array(
                      "*" => "(\-?[0-9\.]+\*\-?[0-9\.]+)",
                      "/" => "(\-?[0-9\.]+\/\-?[0-9\.]+)",
                      "+" => "(\-?[0-9\.]+\+\-?[0-9\.]+)",
                      "-" => "(\-?[0-9\.]+\-\-?[0-9\.]+)"
                 );

    foreach ($operator as $key => $pattern) {

        for ($i=1; $i > 0 ; $i++) {

            if (preg_match($pattern,$ask)) {
                # code...

                preg_match($pattern,$ask,$result);
                $askx = preg_replace($pattern, "x", $ask);
                $asktmp = $result[0];

                /* menyelesaikan operasi dalam kurung */
                preg_match("/^\-?[0-9\.]+/",$asktmp,$nilai1);
                preg_match("/[0-9\.]+$/",$asktmp,$nilai2);
                $returntmp = null;

                if (preg_match("(\-?[0-9\.]+([^0-9\.]{2,2})[0-9\.]+)", $asktmp)) {
                    $nilai2[0] = "-".$nilai2[0];
                }

                if ($key == "*") {
                    $returntmp = $nilai1[0] * $nilai2[0];
                }
                if ($key == "/") {
                    $returntmp = $nilai1[0] / $nilai2[0];
                }
                if ($key == "+") {
                    $returntmp = $nilai1[0] + $nilai2[0];
                }
                if ($key == "-") {
                    $returntmp = $nilai1[0] - $nilai2[0];
                }

                 $ask = preg_replace("/(x)/", $returntmp, $askx);



            }
            else{break;}
            # code...
        }
    }
    return $ask;





}

// function
function prepare($ask)
{

    #do ()
    $i = 1;
    $pattern_kurung = "/\(([^\(\)]+)\)/";
    for ($i=1; $i > 0 ; $i++) {

        if (preg_match($pattern_kurung,$ask)) {
            preg_match($pattern_kurung,$ask,$result);




            $askx = preg_replace($pattern_kurung, "x", $ask);
            $asktmp = $result[1];

            /* menyelesaikan operasi dalam kurung */
            $returntmp = math($asktmp);


            $ask = preg_replace("/(x)/", $returntmp, $askx);


            // break;



        }
        else{

            return math($ask);

            break;
        }


    }



}



// check math syntax
$pattern = "/^(\(*[\+\-]?\(*[\+\-]?\d+(.\d+)?\)*[\+\-\*\/]?)*$/i";
if (!preg_match($pattern, $ask)==true) {
    $return = "math syntax is wrong!";

}
else{
    echo $return = prepare($ask);



}
header("location:index.php?return=".urlencode($return)."&ask=".urlencode($ask));