C program to swap value of two variables without using third variable.

#include<stdio.h>
#include<conio.h>
void main(){
float a,b;
clrscr();
printf("enter two values\n");
scanf("%f%f",&a&b);
printf("before swapping a=%f and b=%f",a,b);
a=a+b;
b=a-b;
a=a-b;
printf ("after swapping a=%f and b=%f",a,b);
getch();
}