Bug of the moment 2008-02-28

As part of my usual mental thumb twiddling when bored, I just confirmed to myself that some code I’m writing did not yet check for out-of-range image numbers in a photo gallery:

Wait … “-0”? Minus nought? That shouldn’t happen.

I’m calculating the number of the gallery page that the image’s thumbnail appears on, and I didn’t write any code to output minus signs, so, surely not … ’Fraid so. In PHP, there is a bug where a calculation of the following variety:

echo ceil(-1 / 10);

will return -0. D’oh.

For the record, this is PHP 5.2.5. I then added, “Cue Perl gloating from you-know-who” but then, I thought, no, surely not …

[rootbeer]$ perl -e "use POSIX; print ceil(-1 / 10) . \"\r\n\";"
-0

Uh huh.

Posted 28th February 2008 – Comments and questions?