RE: [PHP] odd behavior of stripos() with === operator *LAST POST*

On 21 November 2006 00:23, Michael wrote: > At 10:12 AM 11/17/2006 , Ford, Mike wrote: > > > > (integer)===TRUE -- is always FALSE > > (integer)!==TRUE -- is always TRUE > > > > (integer)===FALSE -- is always FALSE > > (integer)!==FALSE -- is always TRUE > > Which brings me to the original point of the post, (which is now > burried in a heap of discussion) a heads-up to the unwary... > > If there is any chance that the needle you are looking for in the > haystack will be found at the first position (index 0), using === > will NEVER return true, What rot, this is a perfectly valid piece of PHP code in which the === will return TRUE if $a does not contain the string 'abc' (and so execute the die()): if (strpos($a, 'abc')===FALSE): die('Invalid string'); endif; > do not do this : > > if ( stripos("abcde","abc")=== TRUE ) {echo "abc found!"} this > will > NEVER be true. No of course not -- why in the world would you do that when TRUE is not one of the documented return values of strpos()?? Sorry, but I think you're still missing the essential point, which is that the opposite of testing for !==FALSE is *not* ===TRUE, but ===FALSE -- in other words, !($x!==FALSE) is the same as ($x===FALSE), or in other other words you invert *only* the *test*, not the *operand*. And it's like this because === and !==, unlike == and !=, do not coerce their operands to Boolean, so something that is !==FALSE is not *necessarily* ===TRUE (although it *is* necessarily ==TRUE). Cheers! Mike --------------------------------------------------------------------- Mike Ford, Electronic Information Services Adviser, Learning Support Services, Learning & Information Services, JG125, James Graham Building, Leeds Metropolitan University, Headingley Campus, LEEDS, LS6 3QS, United Kingdom Email: m.ford@leedsmet.ac.uk Tel: +44 113 283 2600 extn 4730 Fax: +44 113 283 3211 To view the terms under which this email is distributed, please go to http://disclaimer.leedsmet.ac.uk/email.htm