C Program to swap two numbers without using third variable

     Below there is simple and easy program to swap two elements without using third variable along with its flowchart algorithm and output. Let assume there are 2 variable 'a' and 'b'. first we add both the numbers and store it in first variable that is 'a'. Now we subtract 'b' from 'a' (addition of a and b) and store it in b thus we swap b into a. Similarly we do for another variable.


a = a + b
b = a - b
a = a - b

also read: Swapping using pointer

also read: Swapping using third variable

Program:

#include <stdio.h>
#include <conio.h>
/* Swap numbers without using temporary variable By SlashMyCode.com*/
int main()
{
  int a,b;
  printf("Enter value for A= ");
  scanf("%d",&a);

  printf("Enter value for B= ");
  scanf("%d",&b);
  // Code to swap 'a' and 'b'
  a = a + b;
  b = a - b;  // b becomes a
  a = a - b;  // a becomes b

  printf("\n After Swapping: \n\n A= %d, B= %d \n", a, b);
/* Swap numbers without using temporary variable By SlashMyCode.com*/
  getch();
  return 0;

}

Output:

Flowchart:

Algorithm:

1. Start
2. Declare variable a and b.
3. Accept values for a and b.
4. a = a + b; 
5. b = a - b;
6. a = a - b;
7. Print values of a and b.
8. Stop