Technical Functions...!@#$

Is there any header, lets say Math.h for example, that you could use to retreive the absolute value of a number. Technicaly, if I had the string:

75656

and I needed to subtract:

45562

and get:

75656

- 45562

---------------

30114

and so on. I would also need to compensate for other problems like:

34475

-52434

and return:

22041

I am pretty sure that some one could help me, the main goal is to get the positive value from subtraction of two integers. Or maybe I should use a strFormat and use a switch case method. Oh well, I've confused my self enough for one post. If this makes any sense whatsoever, please tell me so!