using System;

public class Program

{

    public static void Main()

    {

        string _filePath = @"C:\Users\Username\source\repos\projectname\projectname\bin\Debug\net5.0-windows";

        string combined1 = System.IO.Path.Combine(_filePath, "test.txt");

        Console.WriteLine(combined1);

        string combined2 = _filePath + @"\test.txt";

        Console.WriteLine(combined2);

        string combined3 = _filePath + "\\test.txt";

        Console.WriteLine(combined3);

    }

}