Determine encoding in a string

If I have a string that will be encoded with Base64, Md5, or some other hash or encryption function, is there a way to at least be able to make a fa开发者_运维知识库ir guess as to what it is?

You can try to guess but with a lot of false results. Md5 always have 32 characters, base64 have a limited set of possible characters, etc.