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From: daemon@decwrl.UUCP (The devil himself)
Newsgroups: net.lang.c
Subject: Using &LABEL
Message-ID: <3480@decwrl.UUCP>
Date: Thu, 30-Aug-84 09:55:23 EDT
Article-I.D.: decwrl.3480
Posted: Thu Aug 30 09:55:23 1984
Date-Received: Sat, 1-Sep-84 14:20:57 EDT
Organization: DEC Engineering Network
Lines: 32

Using &LABEL___________________________________________________________________

> You can take the address of a label using "&foo".
> By the way, is there anything useful you can do with this feature?
> Use it as a function address?  Assigned goto's???  Something else?????

	Good question.  I never use goto's, so I never use labels.  (I may use
a goto someday, but so far I've never had to.)  I could imagine horrible things
like passing the address of a label to another function and executing a goto.
Anyone who does that should probably be strung up by their thumbs.

	VMS RMS has a system function, sys$open(), that takes three arguments:
(1) the address of a File Access Block (FAB), (2) the address of a user-written
error completion routine (optional), and (2) the address of a user-written suc-
cess completion routine (also optional).
	I thought I could use &LABEL to see if the "user-written routine" had
to be a function or just an entry-point, but VAX C doesn't allow use of &LABEL.
Perhaps someone out there running a different type of C on a VMS system could
try it.

	Finally, is &LABEL an officially sanctioned K&R construct?  I don't
have my copy with me so I can't look it up right now...
		<_Jym_>

:::::::::::::::: Jym Dyer
::::'  ::  `:::: Nashua, New Hampshire
::'    ::    `::
::     ::     :: DYER%VAXUUM.DEC@DECWRL.ARPA
::   .::::.   :: {allegra|decvax|ihnp4|ucbvax}!decwrl!dec-rhea!dec-vaxuum!dyer
::..:' :: `:..::
::::.  ::  .:::: Statements made in this article are my own; they might not
:::::::::::::::: reflect the views of |d|i|g|i|t|a|l| Equipment Corporation.