How do you swap two integer values from two variables without using another variable?

let us say the two variables are x & y 

x =5 

y =7 

now we want y =5 and x =7

x = x+y // x =12, y=7

y = x-y // x=12 ,y =5

x = x-y// x =7 and y =5 #

lets say a =10, b =20

a = a ^ b

b = a ^ b

a = a ^ b

a =20, b =10

The other logic is here

x = x*y

y = x/y

x = x/y

Apply the formula for x=5 and y=6

x =5*6 =30

y =30/6 =5

x =30/5 =6

now x=6 & y=5

Already asked here

http://www.bayt.com/en/specialties/q/12096/how-i-can-swap-between-value-variables-using-two-variables-only/