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From: normt@ihlpa.ATT.COM (N. R Tiedemann)
Newsgroups: comp.lang.fortran
Subject: Re: "Interesting" error interpretation by f77.
Message-ID: <5551@ihlpa.ATT.COM>
Date: Fri, 18-Sep-87 08:30:46 EDT
Article-I.D.: ihlpa.5551
Posted: Fri Sep 18 08:30:46 1987
Date-Received: Sun, 20-Sep-87 01:57:32 EDT
References: <5117@jade.BERKELEY.EDU>
Organization: AT&T Bell Laboratories - Naperville, Illinois
Lines: 38
Keywords: FORTRAN parsing, error interpretation.

In article <5117@jade.BERKELEY.EDU>, lagache@violet.berkeley.edu (Edouard Lagache) writes:
> 
>       PROGRAM PRACT
>       ...
>       READ(*,*) NUM1, NUM2
>     SUM = NUM1 + NUM2
>       ...
> 
> 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.
>                                                  Edouard Lagache
>                                                  lagache@violet.berkeley.edu

	Yes, that is the case, Since the two lines where combined 
	with the S acting as a continuation character.
	The F77 compiler (and others) will scan a line looking 
	for assignment statements first, if none found, then 
	it will search for key words.  This gives you the ability to 
	use such words as read, write, etc. as variable names without 
	compiler confusion. 

	When compiler gives syntax error, other
	error messages are irrelevant. (Old Saying).

	This is true in Fortran, but boy is it true in any structured
	language. With a syntax error in C strange messages will appear
	100's of lines later.


	Norm Tiedemann		AT&T Bell Labs
	ihnp4!ihlpa!normt	Naperville, IL 60566

	"Just because we invented the stuff, doesn't mean we have to like it."