Program to Swap two numbers in C#

Write a program to Swap two numbers in C#

In many Interviews, the Interviewer asks the Interviewee to write a program to swap two numbers. There are multiple methods/ways to swap numbers in C#, out of which two popular methodologies are Swapping two numbers with third/temporary variable and another is swapping two numbers without using a third/temporary variable (using + and – arithmetic operator). Let’s see both approaches in detail. 

Swap two numbers by using third/temporary variable:

As you can see in the below image, it’s very simple to swap two numbers with a third temporary variable.

Program to swap two numbers by using third/temporary variable in C# is provided below:

int num1, num2, temp; //Get two number from the user to swap Console.WriteLine("Enter first number"); num1 = int.Parse(Console.ReadLine()); Console.WriteLine("Enter second number"); num2 = int.Parse(Console.ReadLine()); Console.WriteLine("Values before swapping: num1=" + num1 + " and num2=" + num2); temp = num1; num1 = num2; num2 = temp; Console.WriteLine("Values after swapping: num1=" + num1 + " and num2=" + num2); //Console.ReadLine() to hold the screen after the execution of the program Console.ReadLine();

Output:

Swap two numbers without using any third/temporary variable:

As you can see in below image it’s very easy to swap the two numbers without using third variable. 

Program to swap two numbers without using third/temporary variable is provided below:

int num1, num2; //Get two number from the user to swap Console.WriteLine("Enter first number"); num1 = int.Parse(Console.ReadLine()); Console.WriteLine("Enter second number"); num2 = int.Parse(Console.ReadLine()); Console.WriteLine("Values before swapping: num1=" + num1 + " and num2=" + num2); num1 = num1 + num2; num2 = num1 - num2; num1 = num1 - num2; Console.WriteLine("Values after swapping: num1=" + num1 + " and num2=" + num2); //Console.ReadLine() to hold the screen after the execution of the program Console.ReadLine();

Output:

I hope this article will help you in your interview preparation.

Thanks