Can I use the gdb debugger to debug programs built by VC++?
No, not for full (high level source language) debugging. The Microsoft compilers generate a different type of debugging symbol information, which gdb does not understand. However, the low-level (assembly-type) symbols generated by Microsoft compilers are coff, which gdb DOES understand. Therefore you should at least be able to see all of your global symbols; you just won’t have any information about data types, line numbers, local variables etc.