how to identify the extension/type of the file using C#?

Question

i have a workflow where user is allowed to upload any file and then that file will be read.

Now my question is if user have image file xyz.jpg and he renamed it to

Answer 1

If you just need to see if the uploaded file is an Image, just parse it accordingly

try
{
Image image = Bitmap.FromStream(fileData);
}
catch(Exception e)
{
    // this isn't an image.
}