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From: lagache@violet.berkeley.edu.UUCP
Newsgroups: comp.lang.fortran
Subject: "Interesting" error interpretation by f77.
Message-ID: <5117@jade.BERKELEY.EDU>
Date: Thu, 17-Sep-87 01:58:12 EDT
Article-I.D.: jade.5117
Posted: Thu Sep 17 01:58:12 1987
Date-Received: Sat, 19-Sep-87 07:13:59 EDT
Sender: usenet@jade.BERKELEY.EDU
Reply-To: lagache@violet.berkeley.edu (Edouard Lagache)
Organization: University of California, Berkeley
Lines: 42
Keywords: FORTRAN parsing, error interpretation.


    Hello to everyone in FORTRAN land!

         In our introductory FORTRAN classes we have just switched to the
    f77 compiler.  Our first assignment involves students deliberately
    inserting errors in the code in order to gain familiarity with the
    compiler's characteristics.  This is fine when the teaching staff
    understands the errors, but a few days ago I hit an error that I
    couldn't!

      PROGRAM PRACT
      REAL NUM1,NUM2,SUM
      WRITE(*,*) 'Enter two numbers to be added to each other:'
      READ(*,*) NUM1, NUM2
    SUM = NUM1 + NUM2
      WRITE(*,*)
      WRITE(*,*) 'The sum of the two numbers is : ',SUM
      STOP
      END

%f77 practice.f
practice.f:
   MAIN pract:
Error on line 4 of practice.f: syntax error
Warning on line 9 of practice.f: local variable num2 never used
Warning on line 9 of practice.f: local variable read never used
                                                ^^^^
----------------------------------------------> ???? <---------

         After some discussion with the staff, we concluded that
    the assignment was being interpreted before the I/O statement,
    but that doesn't give me much satisfaction.

         My question to the SIG is does this sort of interpretation
    represent a bug?  I am no expert on FORTRAN compiler design, but
    given this sort of funny business, I wonder what sort of weird
    code would be passed on as correct!?!

                                                 Edouard Lagache
                                                 School of Education
                                                 U.C. Berkeley
                                                 lagache@violet.berkeley.edu