Посмотрите здесь, c #
https://msdn.microsoft.com/en-us/library/system.io.streamreader.currentencoding%28v=vs.110%29.aspx
string path = @"path\to\your\file.ext";
using (StreamReader sr = new StreamReader(path, true))
{
while (sr.Peek() >= 0)
{
Console.Write((char)sr.Read());
}
//Test for the encoding after reading, or at least
//after the first read.
Console.WriteLine("The encoding used was {0}.", sr.CurrentEncoding);
Console.ReadLine();
Console.WriteLine();
}