Swapnumbers

#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;  

}