When two lines do not match, you need to search ahead in both files, to see if either file has a line ahead that matches ( or better matches ) the current one. A brute force approach here is going to be very expensive, I would think.
Christian Graus - Microsoft MVP - C++ Metal Musings - Rex and my new metal blog "I am working on a project that will convert a FORTRAN code to corresponding C++ code.I am not aware of FORTRAN syntax" ( spotted in the C++/CLI forum )