Multiple file comparison at a time

Question

Hi

     I am in need to compare the contents of the files..
the concept is as follows..

I have to get two directories containing multiple files from two different persons..
Both directories contain same set of files... I have to compare the contents of corresponding files of two directories and perform string comparison as well as grammar checking and finally i have to merge the correction in that file..

Can anybody give me suggestion or sample code for it?