Swapping values between two variables without a third variable

Here are two ways in which we can swap the values between two variables without the help of any third(temporary) variable:

-> Using method of Addition:

int main(void)

{

unsigned char A, B;

A = 39;

B = 18;

printf("Before:\tA: %d\tB: %d\n", A, B);

/* Swapping Algorithm */

A = A+B;

printf("A: %d\tB: %d\n", A, B);

B = A-B;

printf("A: %d\tB: %d\n", A, B);

A = A-B;

printf("After:\tA: %d\tB: %d\n", A, B);

return 0;

}

-> Using the method of EXOR:

int main(void)

{

unsigned char A, B;

A = 39;

B = 18;

printf("Before:\tA: %d\tB: %d\n", A, B);

/* Swapping Algorithm */

A ^= B;

printf("A: %d\tB: %d\n", A, B);

B ^= A;

printf("A: %d\tB: %d\n", A, B);

A ^= B;

printf("After:\tA: %d\tB: %d\n", A, B);

return 0;

}

=> NOTE: The maximum range of the value to be stored in the variables A & B should be such that, the value of (A+B) will be inside the maximum range of the data type defined for A & B variables.

=> NOTE: The method of EXOR will not work if a and b both have same values. If a and b both have the same values, then both will get cleared (equal to zero) after swapping.