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From: exspes@gdr.bath.ac.uk (P E Smee)
Newsgroups: comp.lang.c
Subject: Re: ambiguous ?
Message-ID: <1989Oct25.090802.19444@gdt.bath.ac.uk>
Date: 25 Oct 89 09:08:02 GMT
References: <11388@smoke.BRL.MIL> <14110@lanl.gov>
Reply-To: exspes@gdr.bath.ac.uk (P E Smee)
Organization: University of Bristol c/o University of Bath
Lines: 23


In article <14110@lanl.gov> jlg@lanl.gov (Jim Giles) writes:
>
>I have still not made my point, but I'm close.  Of course the short
>circuit nature of these operators is valuable.  If they didn't
>short circuit, you would still need a way of providing that functionality.

Valuable indeed.  One of the more common subtle bugs in PL/1 programs is

    if ((ptr ^= null()) & (ptr->thing ^= value))

because PL/1 logical ops don't short circuit.  Algol may have this right,
they offer two sets of logical operators:  AND and OR which do not short
circuit; and ANDTHEN and ORELSE which do.  This gives the programmer total
control, and might be worth considering for some future version of C or
a C offspring.  Both are useful, and making either from the other in a
language which only supports one is fiddly at best.

-- 
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