Question

So I know there have been multiple questions regarding Money and converting to and from cents.
Heck I have even asked another one, but I want to make a slightly different question so I hope there are no duplicates out there.

So I have created a function that takes a Dollar Value and sends it to CENTS.
But I think I have a slight problem with my code and hoping I can get it tweaked a little.

$money4 = "10.0001";
// Converted to cents, as you can see it's slightly off. 
$money41 = "1001";
// So when "1001", get's put in the database, and then I return it back as a Money variable. 
// We get, "$10.01"... but what I have now is a leak in my amounts... as it rounded up to the second point. 

So to do what I have done, I have used to functions I made to do this.

// This essentially gets a DOLLAR figure, or the CENT's Figure if requested.    
function stripMoney($value, $position = 0, $returnAs = "") 
{   
    // Does it even have a decimal?
    if(isset($value) && strstr($value, ".")) {

        // Strip out everything but numbers, decimals and negative
        $value    = preg_replace("/([^0-9\.\-])/i","",$value);
        $decimals = explode(".", $value);

        // Return Dollars as default
        return ($returnAs == "int" ? (int)$decimals[$position] : $decimals[$position]);

    } elseif(isset($value)) {
        // If no decimals, lets just return a solid number
        $value = preg_replace("/([^0-9\.\-])/i","",$value);
        return ($returnAs == "int" ? (int)$value : $value);
    }
}

The next function I use is to generate the CENTS or return it back as dollars.

function convertCents($money, $cents = NULL, $toCents = TRUE)
{
    if(isset($money)) {
        if($toCents == TRUE) {
            // Convert dollars to cents
            $totalCents = $money * 100;
            // If we have any cents, lets add them on as well
            if(isset($cents)) {
                $centsCount = strlen($cents);
                // In case someone inputs, $1.1
                // We add a zero to the end of the var to make it accurate
                if($centsCount < 2) {
                    $cents = "{$cents}0";   
                }
                // Add the cents together
                $totalCents = $totalCents + $cents;
            }
            // Return total cents
            return $totalCents;

        } else {
            // Convert cents to dollars
            $totalDollars = $money / 100;
            return $totalDollars;
        }
    }
}

And the final function that puts everything together. So we just use 1 function to merge the 2 functions together basically.

function convertMoney($value, $toCents = TRUE) {
    if(isset($value) && strstr($value, ".")) {
        return convertCents(stripMoney($value, 0), stripMoney($value, 1), $toCents);

    } elseif(!empty($value)) {
        return convertCents(stripMoney($value, 0), NULL, $toCents);
    }
}

What I have done might be overkill, But I think it’s fairly solid, other than this 1 detail, that I can see.

can anyone help me with these adjustments?

Answer 1

Do not use floating point arithmetic if you need exact answers. This applies to almost all languages, not just PHP. Read the big warning in the PHP manual.

Instead check out BC Math or the GMP extension. The latter only works with integer numbers so you are probably most interested in BC Math.