Program:

The source code to create a user define namespace is given below. The given program is compiled and executed successfully on Microsoft Visual Studio.

//C# program to create a user defined the namespace

using System;

namespace Test.Namespace
{
    class Sample
    {
        public static void Swap(ref int X, ref int Y)
        {
            int Z = 0;

            Z = X;
            X = Y;
            Y = Z;
        }
    }
}
class Program
{
    static void Main()
    {
        int X = 10;
        int Y = 20;

        Console.WriteLine("Before swapping : X " + X + ", Y " + Y);
        Test.Namespace.Sample.Swap(ref X, ref Y);

        Console.WriteLine("After swapping  : X " + X + ", Y " + Y);
        Console.WriteLine();
    }
}

Output:

Before swapping : X 10, Y 20
After swapping  : X 20, Y 10

Press any key to continue . . .

Explanation:

In the above program, we created a user-defined namespace "Test.Namespace" that contains a Sample class. The Sample class contains a Swap() method. The Swap() method will interchange the values of parameters with each other.

Here we also created a Program class that contains the Main() method. In the Main() method, we created two local variables X and Y. Then swap the values using the Swap() method and print the swapped value on the console screen.