Re: reason for a "Notice:.." on one site but not another? (Same code.)

On Mon, 2009-08-10 at 15:40 -0300, Martin Scotta wrote: > This "intelligence" is given by the laziness of the && operator. > > $res = a() && b(); # if a() is false then b() does not evaluate > $res = a() & b(); # b() evaluates no matter a()'s result > > so, order matters. > > On Mon, Aug 10, 2009 at 3:29 PM, Andrew Ballard <aballard@gmail.com> wrote: > > > On Mon, Aug 10, 2009 at 1:50 PM, Ralph Deffke<ralph_deffke@yahoo.de> > > wrote: > > > this is not "intelligence" its just pure math. the '&&' > > > says if BOTH > > > expressions are true then the whole expression is true. > > > > > > so if the first one is false, the whole is false, why checking the next > > one > > > in the underlaying C it would be something like this > > > { > > > if ( expression == false ) return false; > > > if ( expression == false) return false; > > > return true; > > > } > > > > > > ralph > > > ralph_deffke@yahoo.de > > > > That's logically correct, and while PHP does implement this > > "short-circuit" logic, not all languages do. In that regard, I > > appreciate what John meant by saying it makes it look "more > > intelligent." Some languages evaluate each of the conditions to their > > respective boolean results before evaluating the logical operators. > > > > Andrew > > > > -- > > PHP General Mailing List (http://www.php.net/) > > To unsubscribe, visit: http://www.php.net/unsub.php > > > > > > You get the same thing in bash. You call a bunch of commands to run in series, but the next one only runs if it's predecessor was successful. It's frequent to see this sort of command chain: ./configure && make && make install Thanks, Ash http://www.ashleysheridan.co.uk