I have complied the calculator and all the exercise at the end of the chapter and they work better than i expected. I was think bout putting some code in to prevent division by zero, however when i tried divinging by zero in the original code, it already gives output of 1. INF . I can't figure out at all where it is getting this output and why this program is able to deal with division by zero based on the code already contained. Any help or ideas would be greatly appreciated.

Here is a partial possible explanation.

MS VC++ uses IEEE 754 floating point number representation. That representation scheme includes unique encodings of +INF and -INF. (See http://www.psc.edu/general/software/.../ieee/ieee.php .) The run-time library and print code in MS VC++ is such that if a computation result is +INF or -INF, and the result is to be displayed by print code, the result is displayed as such: +INF or -INF, or something that represents those.