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Re: Mysterious warning (comparison between pointer and integer)
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Re: Mysterious warning (comparison between pointer and integer)


  • Subject: Re: Mysterious warning (comparison between pointer and integer)
  • From: Tommy Nordgren <email@hidden>
  • Date: Wed, 11 Jul 2007 12:34:24 +0200


On 11 jul 2007, at 11.01, Stéphane Sudre wrote:

I have a warning in an Obj-C file that is quite mysterious to me:

warning: comparison between pointer and integer

Here is the source code:

// struct in6_addr address_;

- (NSString *) stringValue
{
	char tBuffer[128];

if (IN6_IS_ADDR_LINKLOCAL(&address_) || IN6_IS_ADDR_MULTICAST (&address_))
{
address_.__u6_addr.__u6_addr8[3]=0;
}

if (inet_ntop(AF_INET6,&address_,tBuffer,128)!=NULL) // ******* This is where the warning is reported.
{
return [NSString stringWithUTF8String:tBuffer];
}

return nil;
}


Yet according to the man page:

The function inet_ntop() converts an address *src from network format
(usually a struct in_addr or some other binary form, in network byte
order) to presentation format (suitable for external display purposes).
The size argument specifies the size, in bytes, of the buffer *dst. It
returns NULL


and headers:

const char	*inet_ntop(int, const void *, char *, size_t);


the code looks correct.

I am probably missing something obvious or there's a bug in gcc.


NULL can expand to just a 0 or a (0) or a 0L or a (0L)
with some compiler settings. Replace NULL by the following to silence the warning:
(char *) NULL


-------------------------------------
This sig is dedicated to the advancement of Nuclear Power
Tommy Nordgren
email@hidden



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  • Follow-Ups:
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 >Mysterious warning (comparison between pointer and integer) (From: Stéphane Sudre <email@hidden>)

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