please help!! write a program to swap value of two variables without using third variable

Answer 1

A = A + B
B = A - B
A = A - B

Answer 2

You can use this function to swap two integer numbers:

void swap(int &x, int &y)
{
x = x+y;
y = x - y;
x = x - y;
}

Answer 3

swapping of two numbers x & y. introduce a new variable z.
z=x
x=y
y=z