Path: utzoo!attcan!uunet!lll-winken!ames!hc!lanl!jlg
From: jlg@lanl.gov (Jim Giles)
Newsgroups: comp.lang.fortran
Subject: Re: DO loops, anyone?
Message-ID: <10620@lanl.gov>
Date: 17 Mar 89 23:00:26 GMT
References: <6676@ecsvax.UUCP>
Organization: Los Alamos National Laboratory
Lines: 25

From article <6676@ecsvax.UUCP>, by urjlew@ecsvax.UUCP (Rostyk Lewyckyj):
> [...]
> Pro1 Prohibit gotbranches into the scope of a DO loop, whether to a statement
> well inside the loop or the terminal statement. CThExcept to the DO state-
> ment itsleelf from a statement outside the DO.
> 2 Prohibit the extended range of the DO. i.e. branching out of the DO
> and then back in.
> 3 Require a each DO loop to be terminated by its own ENDDO, which can not
> be the target of a branch.

Your first and second prohibitions are already in the Fortran 77 standard.

ANSI: 11.10.8 Transfer into the Range of a DO-Loop.  Transfer of
      control into the range of a DO-loop from outside the range
      is not permitted.

ANSI: 11.10.1 Range of a DO-Loop.  The range of a DO-loop
      consists of all of the executable statements that appear
      following the DO statement that specifies the Do-loop, up to
      and including the terminal statement of the DO-loop.

These two rules prohibit 'extended range' as well as branches into the
loop - including the terminal statement.

J. Giles