Article View: comp.std.c
Article #5175Re: switch (expression)
From: Michael T Sullivan
Date: Wed, 13 Jul 1988 15:03
Date: Wed, 13 Jul 1988 15:03
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1732 bytes
In article <1988Jul12.105547.13268@light.uucp>, bvs@light.uucp (Bakul Shah) writes:
> dpANS says the expression in ``_s_w_i_t_c_h (expression)''
> must be an integer valued expression. Any chance of
> getting this changed ``must be an integer or ptr valued
> expression''? The current restriction forces one to use
> the messier and longer sequence of ``if..then..else if
> ...'' for pointers...
>
> Note that the switch stmt can be used by casting the ptr
> to a long or an int, but I don't know if this is safe on
> all architectures -- (casts) should be avoided where
> possible.
I don't know about casting should be avoided. I'm looking at shmop(2) manual
page for our 3B2 (shared memory operation) and it says:
"Shmat {which is a char* function -mts} returns the data segment
start address of the attached shared memory segment...
Otherwise, a value of -1 is returned and errno is set to indicate
the error."
Somebody at AT&T must think casting a pointer to an int (or a long) isn't
such a bad idea, unless I'm missing something (it has been known to happen).
--
Michael Sullivan {uunet|attmail}!vsi!sullivan
V-Systems, Inc. Santa Ana, CA sullivan@vsi.com
ons, workstations, workstations, workstations, workstations, workstations, work
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arc1-ca.pugleaf.net!utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!cornell!batcomputer!itsgw!steinmetz!uunet!vsi!sullivanReferences:
<1988Jul12.105547.13268@light.uucp>Show Full Headers
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Path: arc1-ca.pugleaf.net!utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!cornell!batcomputer!itsgw!steinmetz!uunet!vsi!sullivan From: sullivan@vsi.UUCP (Michael T Sullivan) Newsgroups: comp.std.c Subject: Re: switch (expression) Summary: Casting ptr to int Message-ID: <755@vsi.UUCP> Date: 13 Jul 88 15:03:03 GMT References: <1988Jul12.105547.13268@light.uucp> Organization: V-Systems, Inc. -- Santa Ana, CA Lines: 29