Write a method swap () to exchange the values of member variables of two objects of class A (obj 1 and obj2).
void swap(A obj 1，A obj2){
int i，j；
I = obj 1 . a 1；
j = obj 1 . a2；
obj 1 . a 1 = obj 2 . a 1；
obj 1 . a2 = obj 2 . a2；
obj 2 . a 1 = I；
obj 2 . a2 = j；
}