Swapping of two numbers using c language

              To interchange, the value of two variables is known as swapping.
              Example:- Before execution a=2, b=3
                                After execution a=3, b=2

     #include <stdio.h>
  int main()
   {
    int a,b,c;
    printf("Enter value for a\n");
    scanf("%d",&a);
    printf("Enter value for b\n");
    scanf("%d",&b);
    c=a;
    a=b;
    b=c;
    printf("After swapping a=%d b=%d",a,b);
    return 0;   
   }

output: Enter value for a

               10

               Enter value for b

               20

               After swapping a=22 b=11

  swapping of two number without using third variable

      on the above example, we need a third variable c to store the value temporarily but here the following c program only need two variable to swap the values.

   #include <stdio.h>

   int main()

    {

     int a,b;

     printf("Enter value for a\n");

     scanf("%d",&a);

     printf("Enter value for b\n");

     scanf("%d",&b);

     a=a+b;

     b=a-b;

     a=a-b;

     printf("After swapping a=%d b=%d",a,b);

    }

output: Enter value for a

               11

               Enter value for b

               22

               After swapping a=22 b=11