Question

When 10000-100, then result should be 9900.

I tried when I use:-

< ?php

$num1 = number_format(round(10000,1),2);
$num2 = number_format(round(100,1),2);
echo $num1 - $num2;

?>

The above result is -90, that made me realize that the number_format function is not applicable in calculations.

Would there be any way that I can convert a value of number_format (obtained from POST from a previous page) back to numerical value for normal calculation?

Answer 1

To start, the reason is that:

(int) "10,000.00"

resolves to 10 since it stops parsing at the first non-numeric character. Thanks to PHP’s weird type system, this is done implicitly when you subtract the strings.

Yes, you can strip out the commas easily:

$unformatted = str_replace(",", "", $formatted);

but it’s cleaner to just post the raw numeric value (you can still use number_format for the displayed value).

EDIT: It is good practice to explicitly convert numeric strings (without commas) to float (or int) with either a cast ((int) or (float)) or the function version (intval or floatval).