// C# Extension Method

// Doc: https://csharp-extension.com/en/method/1002020/fileinfo-hasextension

​

// @nuget: Z.ExtensionMethods

​

using System;

public class Program

{

    public static void Main()

    {

        string FileName = "folder\\subfolder\\test.txt";

        // C# Extension Method: FileInfo - HasExtension

        if(FileName.ToFileInfo().HasExtension())

        {

            Console.WriteLine("File has extension.");

        }

        else

        {

            Console.WriteLine("File has no extension.");

        }

    }

}