Determine if a byte[] is a pdf file

Question

Is there any way of checking if a byte[] is a pdf without opening?

I have some code to display a list of byte[] as pdf thumbnails. I previously knew all the byte[] w

Answer 1

First four bytes should be: 0x25 0x50 0x44 0x46 (in hex format, in ASCII it's %PDF). "Magic numbers" for another formats you can find here