C# program to demonstrate the use of CreateSubdirectory method

Program

using System;
using System.IO;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main()
        {
            DirectoryInfo d = new DirectoryInfo("mydir");

            d.CreateSubdirectory("sub-dir");

            Console.WriteLine("Sub-Directory created successfully");
            
        }
    }
}

Output

Sub-Directory created successfully.

In this program we create an object of DirectoryInfo class and initialize with a directory-name, then create sub-directory inside given directory.

Note: In above program, we need to remember, when we use "DirectoryInfo" class, System.IO namespace must be included in the program.