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', $total * 100);
}
With the sprintf function you can specify a padding in the format part:
%dis to display an integer,%12dwill right align the integer in a 12 character long string (you can left align with%-12d),%012dwill replace the empty chars with zeros. For other replacement, like a dot:%'.12d.
And there is also a dedicated PHP function to pad a string, str_pad. Used in my method:
public function addTrailingZeros($total)
{
return str_pad($total, 12, "0", STR_PAD_LEFT);
}