ZEND PHP 5 Certification STUDY GUIDE

24 ” PHP Basics
echo !$a;
// outputs 1 (true)
It’s important to understand that all logical operators only work with Boolean values;
therefore, PHP will first convert any other value to a Boolean and then perform the
operation.
The three binary operators are:
&& / and The AND operator evaluates to true if both the left and right
operands evaluate to true. The most commonly-used form of
this operator is &&.
|| / or The OR operator evaluates to true if either the left or right
operands evaluate to true, with the || form being more
commonly used.
XOR The Exclusive OR operator evaluates to true if either the left
and right operands evaluates to true, but not both.
It’s important to understand that PHP employs a very simple shortcut strategy when
executing binary logical operations. For example, if the left-hand side operand of
an AND operation evaluates to false, then the operation returns false immediately
(since any other result would be impossible), without evaluating the right-hand side
operand at all.
In addition to improving performance, this approach is a lifesaver in many situations
where you actually don’t want the right-hand operand to be evaluated at all,
based on the first one.
Other Operators
In addition to all the operators we’ve seen this far, PHP also uses a few specialized
operators to simplify certain tasks. One of these is the error suppression operator
@; when prepended to an expression, this operator causes PHP to ignore almost all
error messages that occur while that expression is being evaluated:
Licensed to 482634 - Amber Barrow (itsadmin@deakin.edu.au)
$x = @mysql_connect();