How to find out if a file exists in C# / .NET?

I would like to test a string containing a path to a file for existence of that file (something like the -e test in Perl or the os.path.exists() in Python) in C#.

System.IO.File:

using System.IO;

if (File.Exists(path)) 
{
    Console.WriteLine("file exists");
} 

System.IO.File.Exists(path)

msdn

Give full path as input. Avoid relative paths.

 return File.Exists(FinalPath);

I use WinForms and my way to use File.Exists(string path) is the next one:

public bool FileExists(string fileName)
{
    var workingDirectory = Environment.CurrentDirectory;
    var file = $"{workingDirectory}\{fileName}";
    return File.Exists(file);
}

fileName must include the extension like myfile.txt