Trailing zeros in PHP

I’ve recently joined Villa-Finder, where lots of large projects where waiting for me with lots of non-optimised/dead code. Here is a little something that help me cleaned up this Symfony2 entity.

The bad and the ugly

I recently found this nice piece of really non-optimised code, playing with concatenation and calculation ~~and sadness 😭~~.

public function addTrailingZeros($total)
{
    $total = (float) $total * 100;
    $totalWithTrailingZeros = "";
    $totalWithTrailingZeros .= ($total / 100000000000) % 10;
    $totalWithTrailingZeros .= ($total / 10000000000) % 10;
    $totalWithTrailingZeros .= ($total / 1000000000) % 10;
    $totalWithTrailingZeros .= ($total / 100000000) % 10;
    $totalWithTrailingZeros .= ($total / 10000000) % 10;
    $totalWithTrailingZeros .= ($total / 1000000) % 10;
    $totalWithTrailingZeros .= ($total / 100000) % 10;
    $totalWithTrailingZeros .= ($total / 10000) % 10;
    $totalWithTrailingZeros .= ($total / 1000) % 10;
    $totalWithTrailingZeros .= ($total / 100) % 10;
    $totalWithTrailingZeros .= ($total / 10) % 10;
    $totalWithTrailingZeros .= ($total / 1) % 10;
    
    return $totalWithTrailingZeros;
}

So here, the author is trying to left align the original number in a 12 characters chain, with trailing zeros.

Example: 149.99 will become 000000014999.

The good

Hopefully, there is a lovely 😘 way to add trailing chars:

public function addTrailingZeros($total)
{
    return sprintf('%012d', $total * 100);
}

With the sprintf function you can specify a padding in the format part:

%d is to display an integer,
%12d will right align the integer in a 12 character long string (you can left align with %-12d),
%012d will replace the empty chars with zeros. For other replacement, like a dot: %'.12d.

And there is also a dedicated PHP function to pad a string, str_pad. Used in my method:

public function addTrailingZeros($total)
{
    return str_pad($total, 12, "0", STR_PAD_LEFT);
}