Re: Style question: Should one check for NULL pointers?

From: "David D. Hagood" <wowbagger@sktc.net>
To: hzhong@cisco.com
Cc: "'Alan Stern'" <stern@rowland.harvard.edu>, linux-kernel@vger.kernel.org
Subject: Re: Style question: Should one check for NULL pointers?
Date: Fri, 11 Jul 2003 09:13:03 -0500	[thread overview]
Message-ID: <3F0EC5EF.7090002@sktc.net> (raw)
In-Reply-To: <01c701c34766$4706cc50$743147ab@amer.cisco.com>

Hua Zhong wrote:

> Not always true. In some cases you know how to handle: just return
> without doing anyting.

That is NOT an error condition - the API specifically allows NULL to be 
passed in, and specifically states that no action will be taken in that 
case.

But consider the following code:

sscanf(0,0);

That IS an error condition - both the string to scan and the format 
string are NULL. In this case sscanf should return EITHER 0 (no items 
matched) or better still -1 (error).

As others have said - ideally, if you have any doubt about a new 
function you are writing being able to succeed, you should write it to 
return a success report.

However, my whole point was that simply checking for null and doing 
nothing when null was not a valid value was violating the rule of "don't 
check if you don't know how to handle".