What namespaces are available?

[Chuck Karish]

In article <535 at garcon.cso.uiuc.edu> mcdaniel at uicsrd.csrd.uiuc.edu
(Tim McDaniel) wrote:
>In article <11982 at haddock.ima.isc.com> karl at haddock.ima.isc.com
(Karl Heuer) writes:
>>	_[a-z0-9][_A-Za-z0-9]*	what I called semi-reserved

>I finally located a reference in K&R 2nd edition (p. 241):
>    External identifiers that begin with an underscore are reserved
>    for use by the library, as are all other identifiers that begin
>    with an underscore and an upper-case letter or another underscore.

>So, were K&R simplifying the issue, or did X3J11 change its mind after
>K&R2 was published, or what?  (Note that I exclude the possibility of
>Karl being wrong.  8-)

	Karl's right about the existence of a special class of names.
	These names are reserved for possible use by the
	implementation, according to Section 4.1.2 of the May, 1988
	draft of the dpANS.  If they are used in application programs,
	the behavior is undefined.  They are, however, usable by
	programmers.

	If you're writing NON-PORTABLE library functions to support
	applications in a specific hardware/software environment, you
	can use this namespace (after checking for actual conflicts on
	your particular system) without polluting the namespace that is
	available for portable programs.


	Chuck Karish	karish at denali.stanford.edu
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			(415) 493-7277