Project program works differently on different systems.

[Apsyc]

I'm doing my final project for my Intro C++ course in which I have A's and extra credit up until now. The project was due last Friday, but I was given an extension to present this Friday instead. My problem is that there are three computers I use to work on this. One at home, one in class, and one in the lab. And on each one the program works differently. Everything that was working when I left the lab is now broken. Everything I fix at home doesn't work in on the class computers. I'm using the same compiler and IDE (CodeBlocks with mingw compiler, from my external drive). I can't get this finish because I have to re-write a lot of code for each system. The code always compiles, but the program never functions as well as it did on the last computer.

Advice?

[Peter87]

Sounds like undefined behaviour. Look out for out of bound array indices, dangling pointers, uninitialized values, etc.

If it's a simple mistake the compiler might be able to help you if you just turn up the warning level. With MinGW/GCC you should at least use the -Wall compiler flag. https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html

Otherwise using a debugger could probably help. I strongly recommend valgrind, it has helped me many times sometimes finding problems I didn't even know I had, but unfortunately it's not available on Windows.