// C# Extension Method
// Doc: https://csharp-extension.com/en/method/1002015/fileinfo-ensuredirectoryexists
// @nuget: Z.ExtensionMethods
using System;
public class Program
{
public static void Main()
string FileName = "folder\\subfolder\\test.txt";
// C# Extension Method: FileInfo - EnsureDirectoryExists
var dir = FileName.ToFileInfo().EnsureDirectoryExists();
Console.WriteLine(dir.FullName);
}