Absolutely, what Mutant said. It's always good to practice. Bit-manipulation functions are low-level enough that it takes some time to get them committed to memory.

As for reinventing the wheel, you don't always realise you're doing it until someone else points out the existing ones.

As a matter of fact, I just discovered an ip2num function in one of my own libraries (written about 3 years ago). I guess I didn't know about those native functions back then either :-)