Question

I have problems to get my percent counter function to get it work with English money format

function calc_proc($price, $savings) {
    $old_price = $price + $savings;

    return (number_format($savings / ($old_price/100)));
}

because of the commas I’m getting bad values

Answer 1

First of all you don’t have to use strings in financial calculations but if you still have to use, you should replace commas with dots. For example,

$a = '1,5';
$b = '2,1';
echo $a + $b; //result 3

// you can avoid this, by replacing comma:
$a = str_replace(',', '.', $a);
//same for $b

Another solution could be setting locale but you’d have issues with dots after that.

In your function it’ll look like this:

function calc_proc($price, $savings) {
    $price = str_replace(',', '.', $price);
    $savings = str_replace(',', '.', $savings);
    $old_price = (float)$price + (float)$savings;

    return (number_format($savings / ($old_price/100)));
}