How to swap without a third variable?

Question

I have to swap two variables with a number value without using a third variable. What is the simple solution?

Answer 1

Let us see one of the method namely by using arithmetic operators. Consider 2 variables say x=50 and y=70 and let us see how to swap the value of two variables that is make x=70 and y=50 without using third variable. This can be done by using following arithmetic operations namely
x= x + y
y= x - y
x= x - y
Which gives
• x= x + y gives x= 70 + 50 an so x is equal to 120
• y= x - y gives y = 120 - 70 which makes the value of y as 50
• x= x - y gives x= 120 - 50 and thus value of x becomes 70

Answer 2

You can achieve it with XOR

int A = ...;
int B = ...;
A = A ^ B;
B = A ^ B;
A = A ^ B;