Re: undefined var has a value

> What's the value of the an undefined var in PHP? > > if $undefined has never been defined before and I do this > > ---------------------------- > if ($undefined == 0) echo "It has zero value"; > else echo "It has nozero value"; > --------------------------- > > It seems to return zero value. > This is not documented in the online PHP manual. > Should I be expecting this in future releases or is this just fluke? It's not a fluke. It's like doing: if('a'==0) echo "a is zero"; That doesn't mean that a is the same as zero, of course, but the numerical equivalent of 'a' is 0 because PHP needs to convert one of the args in order to do a sane comparison. (int)'a' ends up evaluating to 0. Same goes for an undefined value. There is a new operator in PHP 4 which does a strict equality on the two arguments. eg. if('a'===0) "a is zero"; You will note that this does not print "a is zero" like the == version does. -Rasmus