For the first question, there is another way using XOR a = a^y; y=a^y; a=a^y; (2) reverse of a number would be to int reverse(unsigned int iNumber) { int theReversed= 0; int theCopy= iNumber; while(iNumber!= 0) { theReversed= theReversed * 10 + iNumber % 10; iNumber /= 10; } return theReversed; }

a = a + b; b = a - b; a = a - b;