Re: note 8952 added to Comparison Operators

johan@essay.org writes: > $cool = 0; > if($cool == "a"){ > echo "if(cool) == true\n"; > } > > Howcome this test actually returns TRUE ?? Isb't this a bug ? > > http://www.php.net/manual/language.operators.comparison.php First, this note has been deleted; the place for discussion about PHP is the general mailing list at php-general@lists.php.net; the place for bug reports is the bug database at http://bugs.php.net. Please make sure to read the instructions at http://www.php.net/manual/add-note.php before adding another note. As to the question, the above is not a bug; it is the expected behaviour. For an in-depth explanation, read: http://www.php.net/manual/language.types.type-juggling.php http://www.php.net/manual/language.types.string.php#language.types.string.conversion (The above links may get wrapped by mailing; sorry about that.) Anyway, the short answer is that what's going on is PHP's type conversion rules. Since you are comparing an integer ($cool, with the value 0) and a string ("a"), the string gets compared as an integer, meaning that PHP converts "a" to an integer for the comparison. In other words, the line: if ($cool == "a") { ...is interpreted as: if ($cool == (int) "a") { ...which, since converting "a" to an integer results in the value 0, evaluates as true. In PHP 4, there is another equality operator: ===, meaning "identical to". This operator compares both the values and the types of its operands, so that the following: if ($cool === "a") { ...would evaluate as false, since although $cool and "a" have the same integer value, they are of different types. Another way which doesn't require the === operator would be to force the types to compare as you are expecting: if ((string) $cool == "a") { Hope this helps explain it, 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| +----------------------------------------------------------------+