Reading a file as Hexadecimal

I am still fairly new to C#. My background is in IBM mainframe. I have most of the basics down I think but here is what i am unsure of how to do.

I have image files, could be one of 4 or 5 formats. I know from some research the header tag in hex will tell me if the file is a Tif or Jpeg or raster.

IE (4D 4D 00 2A) is a Tif image.

How do I read in this file and translate it to Hex?

Hex is just a view of the raw data, like binary, octal or decimal... or an image for that matter.

I am guessing that what you really need to do is determine the format of the image file? ie, once you've read the first ulong (UInt64) of the file, you just want to look that up in a map code->ImageType? ie, the Hex bit is irrelevent. I understand that the headers are normally given in 4 byte Hex as they are easier to interpretate than decimal.

Untested code follows...

Code:

---

            // create a code to image type mapping table
            Dictionary<UInt64, String> imageFormatlookup = new Dictionary<UInt64, String>();

            // add all of the codes
            imageFormatlookup.Add(0x4D4D002A, "TIF");  // TODO: check the byte ordering is correct
            // etc etc

            // image file for demo purposes
            String imageFilename = @"C:\UnknownImageFile.dat";

            // read the raw data
            Byte[] rawData = File.ReadAllBytes(imageFilename);

            // map the data which is now in memory
            using (MemoryStream ms = new MemoryStream(rawData))
            {
                // read from the memory in 'binary' format
                using (BinaryReader br = new BinaryReader(ms))
                {
                    // get the first 4 bytes
                    UInt64 imageFormat = br.ReadUInt64();

                    String imageType;

                    // see if the first 4 bytes represent an image file
                    if (imageFormatlookup.TryGetValue(imageFormat, out imageType))
                    {
                        //  process the rest of the file, it is of type imageType
                    }

                    br.Close();
                }

                ms.Close();
            }

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For a binary file format, I always read it in binary mode with available functions from File, BinaryReader etc classes, which provide obviously more correct reading and are easier to use than those available in MFC-C/C++.