DIF is a line oriented text file comparison program.  It's
purpose is to compare two files and list the differences.  DIF
identifies portions of two files that are identical, and when it
comes across differences, it attempts to resynchronize the files.

     DIF was written to isolate changes made to the source code
of computer programs which is why it is line oriented, rather
than word or character oriented.  It is designed to work with
ASCII files with lines terminated by carriage return, line feed
sequences.  It is not intended for comparing files created by
Wordstar in document mode or other editors that use non-ASCII
control characters.

     To use DIF, type:

               DIF file1.ext file2.ext   or
               DIF file1.ext file2.ext -flags

     The differences between file1 and file2 will be written to a
disk file with the filename of file1 and the extension "DIF".

     For example:  DIF QKSORT.PAS QKSORT.BAK
will produce a difference file named QKSORT.DIF if any
differences are found.


FLAGS:

     DIF recognizes four flags: Dd, Mn, C and P.  The flags must
appear after "-" with no spaces in between.

     -Dd changes the output drive for the difference file.  "d"
is the name of the disk drive to write the difference file on.

     -Mn, sets the match threshold.  "n" is the decimal number of
consecutive matching lines that qualifies as a match between the
two files.  If this flag is not used, DIF considers 3 consecutive
matching lines to be a match.  If DIF is having trouble
resynchronizing after it locates a difference, the problem can
often be solved by raising the match threshold to 4 or more.

     -C causes the differences to be sent to the console instead
of a disk file.

     -P causes the differences to be sent to the printer instead
of a disk file.

Examples:

               DIF PROG.BAS PROG.BAK -M6DC

     This command will compare PROG.BAS and PROG.BAK, writing the
differences to C:PROG.DIF.  The match threshold is set to 6
consecutive matching lines.


               DIF VERSION1.C VERSION2.C -P

     The differences between VERSION1.C and VERSION2.C will be
printed on the printer.


               DIF MYPROG.FOR PROG.ORG

     The differences between MYPROG.FOR and PROG.ORG will be
written to the file MYPROG.DIF.


               DIF FILE1.ASC FILE.TXT -C

     The differences between FILE1.ASC and FILE.TXT will be
printed on the console.


PROGRAM SOURCE:

     I originally wrote this program in PASCAL MT+.  This version
was modified and compiled using Turbo Pascal.  The source is
included in the library in case anyone wants to modify the
program to work with Wordstar document files, or in case you are
just curious how the program works.  I was working in Argentina
when I wrote the program, so, unfortunately, most of the comments
and variable names are in Spanish.  Sorry.

     To compile, unsqueeze all the *.PAS files and compile
DIF.PAS with the COM Turbo option set.  Have fun.

Bob Ponting
February 27, 1988