file type

Question

I am writing a code to transfer files between computers. At the moment, when user select a file to upload or download, the user also have to select if it is binary or ascii file. So, depend on what they select, the stream is different. Now, I want the code to determine the file type, so the user doesn't need to select it by their self. I have checked file class, fileinfo class and filesysteminfo class etc. But couldn't find any solution for it. Could anybody give me some advice?