Numeric operation using string

Question

I have following string.

$option = '+';
$value = '100';

I want create new value using above parameters.

ex:- $newValue = 222 + 100;

How can i do it using above parameters? as following

$newValue = 222 $option $value; 

Answer 1

function operate($a, $b, $opt){
    switch ($opt) {
        case '+':
            $ret = $a + $b;
            break;
        case '-':
            $ret = $a - $b;
            break;
        case '*':
            $ret = $a * $b;
            break;
        case '/':
            $ret = $a / $b;
            break;
        default:
            throw new Exception('Unsupported operation!');
    }
    return $ret;
}

Edit

$option = '+';
echo operate(222,100,$option);