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From: bhoughto@pima.intel.com (Blair P. Houghton)
Newsgroups: comp.lang.c
Subject: Re: Is there a NULL pointer to functions?
Message-ID: <4429@inews.intel.com>
Date: 27 May 91 20:51:04 GMT
References: <4416@inews.intel.com> <748@taumet.com> <4428@inews.intel.com>
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In article <4428@inews.intel.com> bhoughto@pima.intel.com (Blair P. Houghton) writes:
>"...NULL, which expands to an implementation-defined null
>pointer constant..."
>(ANSI X3.159-1989, sec. 4.1.5, p. 99, ll. 21-22)
>
>"Such a pointer, called a null pointer constant, is guaranteed to
>compare unequal to a pointer to any object OR FUNCTION." [emphasis
>mine --Blair]
>(Ibid, sec. 3.2.2.3, p. 38, ll. 3-4)

Oops.  Total disconnect of the neural fabric.  The word "constant"
should be removed from the 3.2.2.3 quotation.  The entire
paragraph goes:

	"An integral constant expression with the value 0, or
	 such an expression cast to type void *, is called a
	 null pointer constant.  If a null pointer constant is
	 assigned to or compared for equality to a pointer, the
	 constant is converted to a pointer of that type.  Such
	 a pointer, called a null pointer, is guaranteed to compare
	 unequal to a pointer to any object or function."
	 (Ibid., ll. 1-4)

This doesn't abrogate the necessity that comparisons involve
compatible types, however, nor that bare constants take the
type of the object to which they are assigned or compared.

				--Blair
				  "I get me some new specs, someday... @^O"