# Education is not limited to just classrooms. It can be gained anytime, anywhere... - Ravi Ranjan (M.Tech-NIT)

## C# Program to swap two numbers without third variable

We can swap two numbers without using third variable. There are two common ways to swap two numbers without using third variable:

1. By + and -
2. By * and /

Program 1: Using ∗ and /

Let's see a simple C# example to swap two numbers without using third variable.

1. using System;
2.   public class SwapExample
3.    {
4.      public static void Main(string[] args)
5.       {
6.        int  a=5, b=10;
7.        Console.WriteLine("Before swap a= "+a+" b= "+b);
8.        a=a*b; //a=50 (5*10)
9.        b=a/b; //b=5 (50/10)
10.        a=a/b; //a=10 (50/5)
11.        Console.Write("After swap a= "+a+" b= "+b);
12.      }
13.   }

Output:

```Before swap a= 5 b= 10
After swap a= 10 b= 5
```

Program 2: Using + and -

Let's see another example to swap two numbers using + and -.

1. using System;
2.   public class SwapExample
3.    {
4.      public static void Main(string[] args)
5.       {
6.        int  a=5, b=10;
7.        Console.WriteLine("Before swap a= "+a+" b= "+b);
8.        a=a+b; //a=15 (5+10)
9.        b=a-b; //b=5 (15-10)
10.        a=a-b; //a=10 (15-5)
11.        Console.Write("After swap a= "+a+" b= "+b);
12.       }
13.   }

Output:

```Before swap a= 5 b= 10
After swap a= 10 b= 5```