Program of swapping two varibales:
void swap(int *, int *); // This is swap's prototype
int main()
{
int x = 5, y = 7;
swap(&x, &y);
cout << "\n x is now "<< x << " and y is now " << y << '\n';
return 0;
}
void swap(int *a, int *b) // swap is actually defined here
int temp;
temp = *a;
*a = *b;
*b = temp;