Right or wrong - C does not actually have NULL :-) NULL in C is simply mapped to zero. It is useful in logic to sometimes use mapping of logical sentence letters to numbers and use mathematics to perform proof, but that is a special case.
In languages like C, there is no special method of marking a variable as true NULL. Thus, the language has no way of processing three state logic. In SQL, there is a special flag to note that variables are truly null and so it can process three state logic. PHP is odd because it does have a special NULL state but it does not fully support three state logic. But hey - it is a web scripting language - it would be a shame if PHP got all theoretical on us! BTW: >Rome... Oh btw, PHP draws strongly from C, and in C NULL == NULL, and NULL == NULL === TRUE It is NULL === NULL == absurd. So - my approach: I may well use is_null() in low traffic areas on PHP, but then when in an inner loop etc, use === null and maybe comment what it means. Cheers to all AJ Alexander J Turner Ph.D. www.deployview.com www.nerds-central.blogspot.com www.project-network.com -----Original Message----- From: tedd [mailto:[EMAIL PROTECTED] Sent: 26 August 2006 19:24 To: Robert Cummings; tedd Cc: Alex Turner; php-general@lists.php.net Subject: RE: [PHP] Brain Death - [PHP] functions classes At 2:30 PM -0400 8/26/06, Robert Cummings wrote: >On Sat, 2006-08-26 at 12:41 -0400, tedd wrote: > > At 4:51 PM +0100 8/26/06, Alex Turner wrote: >> >And to be very pedantic - as null does not have a type then actually > > >'x === null' should evaluate to absurdity, but PHP is more pragmatic >> >than that ;-) >> >> That's a very good point. >> >> While one NULL variable in php can be compared to another NULL >> variable and produce true, it's not so in MySQL. >> >> In MySQL NULL does not equal NULL -- such comparisons produces NULL >> and not true. Instead you have to use IS_NULL or NOT NULL to check >> for NULL. >> >> So, it's probably best to get into the habit of using is_null. > >I strongly disagree... If I'm writing SQL then I adhere to the language >constructs of SQL, if I'm coding in PHP then I adhere to the language >constructs of PHP. There is no reason why one should forgo better >constructs just because they don't appear in other languages. When in >Rome... Oh btw, PHP draws strongly from C, and in C NULL == NULL, and >last I checked C predates SQL. > >Cheers, >Rob. Rob: As the old woman who kissed the cow said "To each their own." My reasoning is simple and I don't strongly agree, or disagree, with other methodologies. I write in several languages, such as php, js, mySQL, css, and others -- and each have their own constructs. As such, I try to use similar constructs where ever possible. My memory isn't what it used to be. Besides, what Alex Turner said about NULL is correct -- it's absurd to have NULL evaluate to anything. Just because one language allows absurdity doesn't mean you have to practice it. Your mileage may differ and that's Okay. :-) tedd -- ------- http://sperling.com http://ancientstones.com http://earthstones.com -- No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.1.405 / Virus Database: 268.11.6/427 - Release Date: 24/08/2006 -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.1.405 / Virus Database: 268.11.6/427 - Release Date: 24/08/2006 -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
