How to swap two numbers without using third variable.

Swapping of two numbers without using third variable....


#include<stdio.h>
#include<conio.h>
void main()
{
int a,b;
clrscr();
printf("Enter the two numbers: ");
scanf("%d %d",&a,&b);     // let user input a=10 b=20 //
a=a+b;       // a=10+20  i.e. now a=30//
b=a-b;       // b=30-20  i.e. now b=10//
a=a-b;       // a=30-10  i.e. now a=20//
printf("\n After swapping values are : \n a=%d \nb=%d",a,b);
getch();
}