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From: horstman@mathcs.sjsu.edu (Cay Horstmann)
Newsgroups: comp.lang.c++,comp.std.c++
Subject: Re: Default type of "0"
Message-ID: <1991May10.001924.12216@mathcs.sjsu.edu>
Date: 10 May 91 00:19:24 GMT
References: <74609@brunix.UUCP> <1991May7.162035.9247@odin.diku.dk>
Organization: San Jose State University - Math/CS Dept.
Lines: 21

In article <1991May7.162035.9247@odin.diku.dk> juul@diku.dk (Anders Juul Munch) writes:
>
>But I wonder, if we have
>	#define NULL 0
>(which is ANSI C compliant, I don't know if C++ is any different), then
>f(NULL) would call f(int)?! This seems highly unreasonable to me, and it
>looks like yet another good reason why the implicit conversion of 0 to the
>null pointer should be disallowed. 
>Instead, NULL should be used whenever a null pointer is needed. NULL being
>defined as
>	#define NULL ((void*)0)
>And
>	int* ip = 0;
>would then be illegal, and replaced by
>	int* ip = NULL;
>
Beware of DOS header files that define NULL as 0L in the large memory
model!!! 0L is NOT convertible into a pointer. I got bitten by that one
when switching from Glockenspiel to Borland C++

Cay