>I take it that you unzip the zip file and put the files it contains in a folder somewhere
>
>To determine the file type of a file ( apart from looking at the extension) I do not think it is wise to put the contents in a string
>
>I think you have to process the 'raw' contents of the file
>
>Do not use a StreamReader which decodes the bytes into chars depending on an encoding
>
> but a FileStream instead ( https://msdn.microsoft.com/en-us/library/tyhc0kft(v=vs.110).aspx )
>
>You can either
> - read all the bytes in a byte array
>- or use Seek() and read the parts you are interested in with Read() or ReadByte()

Thanks, I will take a look at this by the end of the month.