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From: levy@ttrdc.UUCP (Daniel R. Levy)
Newsgroups: comp.lang.c
Subject: Re: Incomplete structure declarations as opaque data types
Message-ID: <1894@ttrdc.UUCP>
Date: Thu, 10-Sep-87 01:27:04 EDT
Article-I.D.: ttrdc.1894
Posted: Thu Sep 10 01:27:04 1987
Date-Received: Sat, 12-Sep-87 09:47:02 EDT
References: <1396@bloom-beacon.MIT.EDU>
Organization: AT&T, Skokie, IL
Lines: 34

In article <1396@bloom-beacon.MIT.EDU>, newman@athena.mit.edu (Ron Newman) writes:
> The following program is legal, lint-free C, and demonstrates how one can
> implement an abstract ("opaque") data type:
> 
> typedef struct _ThingRec ThingRec, *Thing;
> extern Thing CreateThing();
> 
> main() {
>    Thing thing = CreateThing (4, 7);
>    OperateOnThing(thing);
>    DestroyThing (thing);
>    }

$ lint Thing.c

Thing.c
==============
(8)  warning: main() returns random value to invocation environment
(9)  warning: struct/union _ThingRec never defined
(9)  warning: struct/union ThingRec never defined


==============
name used but not defined
    CreateThing   	Thing.c(5)
    OperateOnThing   	Thing.c(6)
    DestroyThing   	Thing.c(7)
$ uname -a
ttrdc ttrdc 2.0v3 0915 3B-20S
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