COMPARE.TXT                                          26 September 2002
http://ftp.aset.psu.edu/pub/ger/fortran/hdk/compare.txt

              Windows 9x/ME/NT/2000 Fast Binary File Compare
                    H. D. Knoble, hdkLESS at SPAM psu dot edu
         Penn State University Center for Academic Computing

Purpose: To compare two files as though they were BINARY.
         This is NOT to show what files' records are different, but
         rather to do a fast compare of two files for being identical
         or different, and to tell how many characters from the
         beginning of the files match.

Syntax: (1) COMPARE [fileid1 [fileid2]] [/QUIET | -QUIET]
    or  (2) COMPARE
    or  (3) COMPARE c:\path\fname.ext d:\path\=
    or  (4) COMPARE ?  or  /?  or  /h  or  -?  or  -h
    or  (5) From Win 9x/ME/NT/2000 Explorer, drag and drop two files
            to COMPARE.EXE icon or drag one file to this icon and
            second file to the TITLE BAR of the resultant DOS prompt
            screen.

where:  (1) compares fileid1 with fileid2; COMPARE recognizes
            Windows 9x/ME/NT/2000 long file names and works in 32-bit
            (protected) mode.
        (2) prompts for fileid2 and or fileid1
        (3) sets the fname.ext portion of fileid2 equal to the
            fname.ext portion of fileid1.
        (4) Displays brief help.

Use:  See the COMPARE.EXE module in the same FTP subdirectory as
      COMPARE.TXT. That is the URL:
      ftp://ftp.cac.psu.edu/pub/ger/fortran/hdk/compare.exe
      COMPARE.EXE may be run from Windows START/RUN
      command, or MS-DOS Prompt, or as an Icon (since it will prompt
      for two fileids), or an Icon that can be drag and dropped to.
      COMPARE.EXE may be called from another Windows app using the
      two argument call, including from Windows Explorer to drag and
      drop one or two files a time to the COMPARE.EXE Icon.

Results: The fileids and number of characters matched with the compare
         is displayed along with a message indicating that either
         files are identical or that they differ. If they differ,
         a character count (file offset origin 1) and Hexadecimal
         representation of the first chararacter that differs is
         displayed. DOS Errorlevel is set to zero if the files are
         identical, or 1 otherwise. If ASCII file are compared, line
         end sequence CR and/or LF are counted and compared; that is,
         all files are treated as BINARY. The option /QUIET /quiet
         -QUIET -quiet may be used to suppress displayed results;
         this is for programs or scripts invoking COMPARE and relying
         on Errorlevel return code.

Examples: COMPARE ?    displays brief help (command syntax).
          COMPARE c:\WINDOWS\xxx.dll  a:\xxx.dll         compares the
                  two files and displays messages indicating results
                  as shown above
          COMPARE c:\WINDOWS\xxx.dll  a:\xxx.dll /quiet  compares the
                  two files and suppresses displayed output.
          COMPARE c:\WINDOWS\xxx.dll A:\=               sets second
                  fileid equal to a:\xxx.dll and does the compare.

          To create a DOS Batch file that compares all files in one
          subdirectory with those of same filename.ext in another
          subdirectory use Batch commands:
          REM binary compare each file in %1 to companion in %2
          REM and put in log file COMP.LOG.
          for %%f in (%1\*.*) do COMPARE %%f %2\= >> comp.log

          Source code, subprograms FGETCMD and FGETSIZE, give several
          vendor specific codes to: (1) interrogate option string passed
          to COMPARE.EXE;  and (2) to get file sizes of the input files.

Compilers: COMPARE.EXE is the compiled result of COMPARE.FOR using
           Compaq (formerly Digital) Visual Fortran, Version 6.6B
           with options: /optimize:5 /nocheck
           COMPARE.FOR will also compile and run using: Salford FTN95,
           Lahey F90/LF95, and Watfor77(Old DOS version); see comments
           for source code changes.

Author: Herman D. Knoble, Penn State Center for Academic Computing
        hdk at psu dot edu, +1 (814) 865-0818

Also see: Windows 9x/ME/NT/2000 and DOS native command, FC /?
          Note that FC can produce voluminous output which may not be
          suppressable; so FC does not produce a summary like COMPARE.
          Also FC compares files one character at a time, so is
          much slower than COMPARE - prohibitively so for very large
          files. One thing FC does do that COMPARE does not (without a
          batch file - see above) is handle wildcard fileids; that is,
          sets of files in one command.

          For a good "intelligent" free ASCII, HTML, or MS Word file
          comparison program for Win32 platforms, see:
             http://www.ComponentSoftware.com/csdiff/dlcsdiff.htm
          This shows (highlights in one of two formats) HOW two files
          are different. In addition to intelligently comparing two
          files, CSDIFF also compares two directory structures for
          identical file content; and it does this by actually comparing
          each file pair in the two subdirectories bit for bit; it then
          produces a report summarizing a comparison of the subdirectory
          contents. There is an option for including the "children"
          subdirectories in the CSDIFF directory compare.

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