Himbanta M.

#include<stdio.h>
int main()
{
int a=10, b=20;
printf("Before swap a=%d b=%d",a,b);
a=a+b;//a=30 (10+20)
b=a-b;//b=10 (30-20)
a=a-b;//a=20 (30-10)
printf("\nAfter swap a=%d b=%d",a,b);
return 0;
}
Output:

Before swap a=10 b=20
After swap a=20 b=10
Program 2: Using * and /
Let's see another example to swap two numbers using * and /.

#include<stdio.h>
#include<stdlib.h>
int main()
{
int a=10, b=20;
printf("Before swap a=%d b=%d",a,b);
a=a*b;//a=200 (10*20)
b=a/b;//b=10 (200/20)
a=a/b;//a=20 (200/10)
system("cls");
printf("\nAfter swap a=%d b=%d",a,b);
return 0;
}

Without using any variable in C++:

#include<stdio.h>
#include<stdlib.h>
int main()
{
int a=10, b=20;
printf("Before swap a=%d b=%d",a,b);
a=a*b;//a=200 (10*20)
b=a/b;//b=10 (200/20)
a=a/b;//a=20 (200/10)
system("cls");
printf("\nAfter swap a=%d b=%d",a,b);
return 0;
}
With using third variable:

#include<stdio.h>
int main() {
double first, second, temp;
printf("Enter first number: ");
scanf("%lf", &first);
printf("Enter second number: ");
scanf("%lf", &second);

// Value of first is assigned to temp
temp = first;

// Value of second is assigned to first
first = second;

// Value of temp (initial value of first) is assigned to second
second = temp;

printf("\nAfter swapping, firstNumber = %.2lf\n", first);
printf("After swapping, secondNumber = %.2lf", second);
return 0;
}