#41228 [Opn]: Side-effects for logical operators

ID: 41228 Updated by: rquadling@php.net Reported By: terminatorul at gmail dot com Status: Open Bug Type: Documentation problem PHP Version: Irrelevant New Comment: Agreed. <?php // Echo's F and does NOT set $a. echo (False && ($a=1)) ? 'T' : 'F'; // Echo's T, sets $b but does not set $c. echo (($b=2) || False || ($c=3)) ? 'T':'F'; // Turn off notices about undefined variables for $a and $c. error_reporting(E_ALL & ~E_NOTICE); // Rather than "1 2 3", we get just " 2 ". echo "$a $b $c"; ?> Previous Comments: ------------------------------------------------------------------------ [2007-04-29 18:29:26] terminatorul at gmail dot com Description: ------------ The manual page for logical operators http://www.php.net/manual/en/language.operators.logical.php should warn users that the right-hand operand of && or || will never be evaluated if that is not necesary For example when doing: $result = FALSE && mysql_query($query); than the mysql $query will never get executed. Or at least the page should advise users to never rely on side-effects. Reproduce code: --------------- http://www.php.net/manual/en/language.operators.logical.php Expected result: ---------------- The page should say something like: For the binary logical operators the second operand will never be evaluated when it is clear from the first operand what the result will be. For example the code $prev_status = FALSE; $crt_status = $prev_status && mysql_query($query); echo mysql_affected_rows(); will never execute the query, simply because $crt_status will be FALSE no matter what mysql_query() would return. Actual result: -------------- Right now I can see nothing about side-effects in the page. ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/?id=41228&edit=1