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From: fisher@qut.edu.au
Newsgroups: comp.lang.fortran
Subject: Re: Is this kosher?
Message-ID: <1991Jan31.103435.23238@qut.edu.au>
Date: 31 Jan 91 15:34:35 GMT
References: <2787@dftsrv.gsfc.nasa.gov>
Organization: Queensland University of Technology
Lines: 36

In article <2787@dftsrv.gsfc.nasa.gov>, jim@jagubox.gsfc.nasa.gov (Jim Jagielski) writes:
> 
> Tell me, is jumping into an IF block statement legal (I know it ain't
> pretty)... for example:
> .
> .
> Is the above legal and acceptable... I can't find any references to it in my
> books...
>

I assume we are talking about FORTRAN 77.
 
COMMENCE HOBBY HORSE

  As recently discussed there is only one authoritative book and it 
  should be consulted by anyone answering this sort of question. It is 
  ANSI X3.9-1978 and is easily obtained from the American National 
  Standards Institute or your national Standards Organisation.

END HOBBY HORSE

11.6.2 defines an IF-Block

11.6.3 paragraph 2 says

"Transfer of control into an IF-block from outside the IF-block is 
prohibited."

11.7 and 11.8 include equivalent statements for ELSE IF-blocks and ELSE 
blocks.

I cannot talk for the writers of ANSI X3.9-1978 but it is not hard to 
imagine that this prohibition simplifies the task of the writers of 
optimising compiler writers.

Bill