note 69022 deleted from language.operators by danbrown
| From: | danbrown@php.net | Date: | Fri, 30 Jan 2009 20:41:29 +0000 |
| Subject: | note 69022 deleted from language.operators by danbrown | ||
| References: | 1 | Groups: | php.notes |
| Request: | Send a blank email to php-notes+get-150001@lists.php.net to get a copy of this message | ||
Note Submitter: T Chan
----
In response to 26-Mar-2001 08:53, parens don't need to have precedence. There's only one
way to convert them to a syntax tree. I can't think of a sensible reason it could be ambiguous
either (and sensible language designers will make ( always pair with ) so there can't be any
ambiguity).
In response to 12-Aug-2005 08:47, you can do <?php $myvar OR ($myvar = 1); ?>, or the
equivalent <?php !$myvar AND $myvar = 1; ?>, and if you have to use ifs, <?php if(!$myvar)
{ $myvar = 1; } ?> will do just fine (though in general, I'd be careful using boolean
expressions as an indicator of success/failure when 0 could be a valid value. And you probably want
to use isset($myvariable)).
In response to the manual, associativity doesn't determine the order of evaluation - it
determines how it's "bracketed": a=b=c=1 is equivalent to a=(b=(c=1)), but a is
evaluated first (an important point if evaluating a has side-effects)
<?php
function one($str) {
echo "$str";
return 1;
}
$a = array(1,2);
$a[one("A")] = $a[one("B")] = 1; // outputs AB
?>