Re: is this a bug in PHP4?

phpmail@intranet.alpsnet.com writes: > > <? > $var = 0; > echo "--$var--<br>"; > if($var == "am") echo "var == am is true"; > else echo "var == am is false"; > ?> > > If you run that on PHP 4.0 or PHP 4.0.3pl1 you will see that > > if($var == "am") evaluates to TRUE > > This looks like a bug because I just set $var to zero. > > zero != "am", right? Nope. It's a bit weird at first, but 0 does, indeed, == "am". You want to use '==='. An explanation is given here: http://www.php.net/manual/language.types.string.php#language.types.string.conversion (That link might wrap in your mail program.) I don't have a lot of time right now, but basically it happens because in the case above, "am" gets converted to int for the purpose of the comparison. When converting a string to int, the int value becomes the value of any digits before the first non-digit character in the string. So "23am" becomes 23, "4f7oo" becomes 4, and so forth. Since the string "am" doesn't have any digits before the 'a', it evaluates to 0, and thus 0 == "am" (really, 0 == 0) evaluates as true. Use '===', which makes sure that a) variables are equal, and b) they are of the same type. Hope this helps, Torben -- +----------------------------------------------------------------+ |Torben Wilson <torben@php.net> Netmill iTech| |http://www.coastnet.com/~torben http://www.netmill.fi| |Ph: 1 250 383-9735 torben@netmill.fi| +----------------------------------------------------------------+