C Program to swap 2 nos without using 3rd variable

Program to swap 2 nos without using 3rd variable-

#include<stdio.h>

void main()

{

int a,b;

printf("Enter two numbers ");

scanf("%d %d",&a,&b);

printf("Before swaping a=%d b=%d",a,b);

a=a+b;

b=a-b;

a=a-b;

printf("\nAfter swaping a=%d b=%d",a,b);

} 

Output-

Enter two numbers 10 20

Before swaping a=10 b=20

After swaping a=20 b=10