C# - Swap two numbers

There are two common ways to swap the value of two variables:

• Swap the value of two variables using a temporary variable
• Swap the value of two variables without using temporary variable

Method 1: Swap the value of two variables using a temporary variable

In the example below, the initial value of variables x and y are 10 and 25. A temporary variable called temp is created to store the value of x and then the value of y is assigned to x. Finally, value of temp (which stores values of x) is assigned to variable y. The final value of variables x and y after swap are 25 and 10 respectively.

using System;

class MyProgram {
  static void swap(int x, int y) {
    Console.WriteLine("Before Swap.");
    Console.WriteLine("x = " + x);
    Console.WriteLine("y = " + y);

    //Swap technique
    int temp = x;
    x = y;
    y = temp;

    Console.WriteLine("After Swap.");
    Console.WriteLine("x = " + x);
    Console.WriteLine("y = " + y);
  }  

  static void Main(string[] args) {
    swap(10, 25);
  }
}

The above code will give the following output:

Before Swap.
x = 10
y = 25
After Swap.
x = 25
y = 10

Method 2: Swap the value of two variables without using temporary variable

+ operator is used to swap the value of two variables. In this method no temporary variable is used. See the example below for syntax.

using System;

class MyProgram {
  static void swap(int x, int y) {
    Console.WriteLine("Before Swap.");
    Console.WriteLine("x = " + x);
    Console.WriteLine("y = " + y);

    //Swap technique
    x = x + y;
    y = x - y;
    x = x - y;

    Console.WriteLine("After Swap.");
    Console.WriteLine("x = " + x);
    Console.WriteLine("y = " + y);
  }  

  static void Main(string[] args) {
    swap(10, 25);
  }
}

The above code will give the following output:

Before Swap.
x = 10
y = 25
After Swap.
x = 25
y = 10

Similarly, others operators can also be used in this method. Please see the page: C# - Swap two numbers without using Temporary Variable.