swap two numbers in c without using third variable code example

Example 1: swap two numbers in c

#include <stdio.h>
int main() {
    double a, b;
    printf("Enter a: ");
    scanf("%lf", &a);
    printf("Enter b: ");
    scanf("%lf", &b);

    // Swapping

    // a = (initial_a - initial_b)
    a = a - b;   
  
    // b = (initial_a - initial_b) + initial_b = initial_a
    b = a + b;

    // a = initial_a - (initial_a - initial_b) = initial_b
    a = b - a;

    printf("After swapping, a = %.2lf\n", a);
    printf("After swapping, b = %.2lf", b);
    return 0;
}

Example 2: c program to swap two numbers using call by reference

#include <stdio.h>
 
void swap(int*, int*);
 
int main()
{
   int x, y;
 
   printf("Enter the value of x and y\n");
   scanf("%d%d",&x,&y);
 
   printf("Before Swapping\nx = %d\ny = %d\n", x, y);
 
   swap(&x, &y); 
 
   printf("After Swapping\nx = %d\ny = %d\n", x, y);
 
   return 0;
}
 
void swap(int *a, int *b)
{
   int temp;
 
   temp = *b;
   *b = *a;
   *a = temp;   
}

Example 3: swap 2 integers without using temporary variable

using System;

class MainClass {
  public static void Main (string[] args) {
    int num1 = int.Parse(Console.ReadLine());
    int num2 = int.Parse(Console.ReadLine());
      num1 = num1 + num2; 
      num2 = num1 - num2; 
      num1 = num1 - num2; 
      Console.WriteLine("After swapping: num1 = "+ num1 + ", num2 = " + num2); 
    Console.ReadLine();
  }
}