What problems did you encounter while developing your solution? How do you plan to overcome them?/How did you overcome them?

While doing an assignment, I encountered a problem in which I thought everything was fine but the compiler kept on giving me unexpected answers. It is a program that asks the user for grades and calculates their GPA. The compiler kept on giving the wrong calculations although the code seems to be fine. I have not overcome the problem yet, but next class, I plan to scan the whole code and find the bug. It is probably an int / double problem.