'===========================================================================
' Subject: COMPARE 2 FILES FOR DIFFERENCES   Date: 06-29-98 (00:08)       
' Author:  Matt Gulden                       Code: QB, QBasic, PDS        
' Origin:  www.thrillhaus.com/basic.html   Packet: MISC.ABC
'===========================================================================
' COMPARE.BAS
' by Matt Gulden
' http://www.thrillhaus.com/
' A *fast* file compare routine. You need quickbasic to run this...
' It's most useful when it's compiled... Do whatever the heck you want
' with this code.

ON ERROR GOTO ErrorHandling

IF INSTR(COMMAND$, " ") THEN
  FILE1$ = LEFT$(COMMAND$, INSTR(COMMAND$, " ") - 1)
  FILE2$ = RIGHT$(COMMAND$, LEN(COMMAND$) - INSTR(COMMAND$, " "))
ELSE
  PRINT "Usage: COMPARE file1 file2": END
END IF

' Set the variable FILE$ to the file that we're opening so error handling
' can tell us, in the event of a file i/o error, which file doesn't exist
FILE$ = FILE1$

OPEN FILE1$ FOR INPUT AS 1

' Same as last comment
FILE$ = FILE2$

OPEN FILE2$ FOR INPUT AS 2

WHILE NOT EOF(1) AND NOT EOF(2)
 
  ' Get the first byte from each file
  BYTE1$ = INPUT$(1, 1)
  BYTE2$ = INPUT$(1, 2)
 
  ' Compare them
  IF NOT BYTE1$ = BYTE2$ THEN
    IF LOC(1) = 1 THEN
      PRINT "Files differ at first byte"
    ELSE
      PRINT "Files differ at"; LOC(1); "bytes"
    END IF
    END
  END IF

WEND

PRINT LCASE$(FILE1$); " and "; LCASE$(FILE2$); " are exactly the same..."
CLOSE
END

ErrorHandling:
IF ERR = 53 THEN
  PRINT "File Not Found: "; FILE$
ELSE
  PRINT "Error:"; ERR
END IF
END