I am not sure what you are trying to do. Perhaps you could be a little more specific by providing an example, such as a small sample of the file's contents. Are you trying to parse a file which is in the CVS repository itself (an RCS file with a ",v" suffix)?

If you merely want to get the current version of a file, you can just use a command (on *nix) like:

cvs checkout file
[download]

But, you could just google cvs to find out more than you ever wanted to know.