String Comparison Result
As Matej already mentioned, use:

strcmp(a, b) != 0


If you compare a and b, what you are actually doing is comparing two pointers (to the text characters). These pointers a and b are stored at different locations in memory, although the content itself can be the same.

See it as this:

a   memory location 0x12345: "Bang"
b   memory location 0x1234A: "Bang"    (5 memory locations further)