None can "urgently" answer this question. There are maths behind it. Search google for binary logic and examples of bitwise operations. I then suggest to look for "NOT", "AND", "OR" and "XOR" operations and their truth tables. Then search how these are implemented in C (~, &, | and ^ respectively). Make a small demo program (no more than 10 lines) and test these operations. Use windows calculator for help, so that you can easily convert decimal to binary values. See if the values from these operations change according to the operator's truth table and that should be it!