RE: [PHP] Inconsistent String Definition (string position starts at zero)?

On Sun, 26 Nov 2000, Adam Warner wrote: > Thanks Ignacio, > > !==false worked! I thought the extra = was a typo. I really appreciated the > very useful and prompt response. I've still got to try and understand why > that worked. The manual states: > > One last thing worth mentioning is the truth value of expressions. In many > events, mainly in conditional > execution and loops, you're not interested in the specific value of the > expression, but only care about > whether it means TRUE or FALSE (PHP doesn't have a dedicated boolean type). The PHP manual is lying about there not being a Boolean type in PHP 4. True and false exist just as much as 4 or "Hello, world!" or Array(1 => "one", 2 => "three"). It just so happens that 0, "", and Array() evaluate to false in a conditional. > The truth value of > expressions in PHP is calculated in a similar way to perl. Any numeric > non-zero numeric value is TRUE, > zero is FALSE. Be sure to note that negative values are non-zero and are > thus considered TRUE! The > empty string and the string "0" are FALSE; all other strings are TRUE. With > non-scalar values (arrays > and objects) - if the value contains no elements it's considered FALSE, > otherwise it's considered TRUE. > > -- > > OK so there does appear to be a manual omission. But what's the significance > of the extra symbol because !=false doesn't work? > > I'll give it a go: > !=false evaluates whether the expression is not zero. Or "". False is funny in that it evaluates to either depending on the context. > !==false evaluates whether the function returns false. > > So why doesn't ===true evaluate whether the function returns not false? strpos() never returns true. It only returns 0, a positive integer, or false. > > Thanks again, > Adam > -- Ignacio Vazquez-Abrams <ignacio@openservices.net>