ZEND PHP 5 Certification STUDY GUIDE

PHP Basics ” 29
// Evaluates to true
break;
default:
// Will only be executed if no other conditions are met
break;
}
A switch statement evaluates the initial expression ($a in this case) only once, and
then compares it against the individual case values; if a match is found, it will continue
to execute code until it encounters a break statement. Note that the use of
break is required—or the interpreter will continue executing code even if it finds another
case. Finally, if none of the test cases match, the interpreter executes the code
block in the default block.
Iterative Constructs
Iterative constructs make it possible to execute the same portion of code multiple
times. PHP has four of these, although only two of them are necessary to the functioning
of a language.
The simplest iterative constructs are the while() and do...while() loops; they allow
you to perform a series of operations until a condition evaluates to false:
$i = 0;
while ($i < 10) {
echo $i . PHP_EOL;
$i++;
}
$i = 0;
do {
echo $i . PHP_EOL;
$i++;
} while ($i < 10);
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As you can see, these two types of loop are very similar; the only significant difference
is in when the condition is checked to determine whether the code inside the
construct should be executed or not. In a while() loop, the check is performed every
time the execution point enters the loop—this means that, if the condition is never