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

Are there specific file formats you need to detect? It makes the task a lot easier if you can narrow it down to a few formats that can be identified by the contents of the file.

If you need to detect a broad range of file types, there are third party toolkits you can use, but I'll warn you that they tend to be very expensive. The two I am familiar with are Stellent's (now Oracle's) Outside In, and Autonomy Keyview. Both provide programmer toolkits.