Why don't you just keep the part about not having letters? That would prove that it's numberic on its own.

Instead of "filtering out", try "filtering in". There are many characters that you do not account for, and would be silly to try. A simpler approach would be to look at character for character to determine if each character is a 0 through a 9 - as apposed to searching for everything else.

Another even simpler approach would be to use regex. ie: boost::regex

- Billism