How can we switch two variables values using only two variables..?

Answer 1

It's a data manipulation trick, there is more than one way.

For integers:

Use 1 variable to hold difference.
Then use difference to swap the other over variable.
Then use the value and difference get the other value back.

Answer 2

how ?

Answer 3

y = y - x; //y holds the difference
x = x + y; //x holds the y value
y = x - y; //y holds the x value;