[Tutor] Comparing lines in two files, writing result into a third file

R. Alan Monroe R. Alan Monroe" <amonroe@columbus.rr.com
Wed Apr 23 08:10:02 2003

> I have two files, file1.txt and file 2. txt, each containing numbers.  I
> want to compare the numbers in the files and put an asterisk at the end of
> the numbers that match, writing the result into a third file, .

Are the input files always going to be sorted?