novice for variables questions

[eluser]syntaxerror[/eluser]
ok,
i would like to compare files in a directory.
there will be 2 directories, KE dir and QC dir.
in this directory there are files.
these files have the same filename.
so, all files in the directories will be in an array.
i will compare each file one by one and check if there is dissimilarities and
if there is, i will get that word and count it as major error or minor error depending
on the field.
its like comparing 2 files with errors, from KEY ENTRY DIR and QUALITY CONTROL DIR. checking errors.
im on my way to designate errors in Major and Minor

do you have any idea please.....
i want to integrate my program into codeigniter so that i know how to use it
thanks