Question

I put a check in a script that makes sure a total is correct. What it does is looks at the total as it is stored in the database and then using other variables, calculates what the total should be.

If these two values – the stored total and the calculated total – are not equal, it’s a problem so I want it to send an email alert.

Here’s the snippet of the code I use to do this:

$storedTotal     = $row['total']; # Pulls from a varchar field in the database $calculatedTotal = $subtotal + $tax + $shipping - $deduct;  # Make sure the stored total equals what it should (the calculated total) if($storedTotal != $calculatedTotal) {     # Send an alert     mail('[e-mail]','Total check fail','Stored total:$storedTotal \n\n Calculated total:$calculatedTotal \n\n'); } 

It seems very simple, however, I repeatedly get emails from it that looks like this:

Stored total:23.40  Calculated total:23.40 

As you can see, the two values appear the same.

Can anyone see any reason why they’re not showing as equal? I’m not using a strict equality check so it shouldn’t be getting tripped up on types.

Answer 1

Try converting and rounding before you compare them:

$storedTotal        = round(floatval($storedTotal), 2); $calculatedTotal    = round(floatval($calculatedTotal), 2);  if ($storedTotal != calculatedTotal) { ...