What sort algorithm does PHP use?

Internally speaking, which algorithm(s) does PHP use to implement the various sort functions it offers? It seems like the usort variants might use a different algorithm than the built in sorts, but I wanted to know.

Where would I even find this information?

Thanks!

Answer

You could find the information by looking at the php manual. http://php.net/sort says PHP uses an implementation of Quicksort. Failing that, you could always trudge through the PHP source code itself.