Re: Writing bulletproof code

From: Programmer Dude (Chris_at_Sonnack.com)
Date: 01/06/04 

Date: Tue, 06 Jan 2004 12:19:20 -0600

"Arthur J. O'Dwyer" wrote:

I guess my question is...

> If I want to write a function in C that takes a user-id
> as a parameter, I not only have to check that the string is
>
> 1) not empty
> and 2) well-formed
>
> but also, because of the form of the language, I must check that
> it is
>
> 3) not a null pointer
>
> and *also*, because of the lack of "check-ability," I am *unable*
> to check that it is
>
> 4) a null-terminated string
> 5) not a wild pointer
> 6) not a floating-point value reinterpreted as a string
> 7) not a pointer to a value that may change at whim
>
> ...and so on.

...what are the relative chances of the above errors? IME, as
initializing to NULL, or using NULL as an error return value, is
very common, erroneously receiving a NULL pointer has a fairly
high likelihood.

Thus, IMO, it is reasonable to check for. 

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