File encoding and code page recognition

[Davider]

@Gintaras
Thanks for your help, it works well

I have a question
the example above has only one file, if there are two thousand files I'm going to traverse, each file is about 2M in size, the speed of using C# functions, and using QM code completely, about how much difference?  
What do you suggest? Thanks again
As I currently know, using powershell is slow