MainClass.cs

using System;
using System.Threading;
using System.Globalization;

class MainClass
{
  public static void Main (string[] args)
  {  
    // Will print the current culture, which
    // depends on your system settings
    Console.WriteLine(Thread.CurrentThread.CurrentCulture);

    // Will print the current UI culture, which
    // depends on your system settings
    Console.WriteLine(Thread.CurrentThread.CurrentUICulture);

    var french = new CultureInfo("fr");

    Thread.CurrentThread.CurrentCulture = french;
    Thread.CurrentThread.CurrentUICulture = french;

    // Will print "fr"
    Console.WriteLine(Thread.CurrentThread.CurrentCulture);

    // Will print "fr"
    Console.WriteLine(Thread.CurrentThread.CurrentUICulture);
  }
}