// 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.");