Write a C program Swap two values without 3rd variable

 Write a C program Swap two values without 3rd variable.

#include<stdio.h>

#include<conio.h>

void main()

{

    int a,b;

    clrscr();

    printf("Enter number: ");

    scanf("%d",&a);

    printf("\nEnter number: ");

    scanf("%d",&b);

    a=a+b;

    b=a-b;

    a=a-b;

    printf("a=%d",a);

    printf("b=%d",b);

    getch();

}