What would be the best technique to validate a file name? I am also looking to see if someone has already done that.

What I need to have is a function which will validate a string to see if this is a valid file name. The string can be something like c:\data\client1\reports\monthly.txt.

The first part is to validate for all non accepted character in the string.

The second part is to validate is the path is valid.

Any technique, advise or sample is appreciated.