ZEND PHP 5 Certification STUDY GUIDE

30 ” PHP Basics
true, the code inside the loop will never be executed. In a do...while() loop, on the
other hand, the check takes place at the end of each iteration of the loop—meaning
that, even if the condition never evaluates to true, the contents of the loop will be
executed at least once.
The for and foreach constructs are specialized looping mechanisms that can be
used to essentially encapsulate a while() loop in a slightly more readable form:
for ($i = 0; $i < 10;$i++) {
echo $i . PHP_EOL;
}
i
As you can see, the for declaration contains three portions, separated by semicolons.
The first one contains an instruction (or series of instructions separated by a comma)
that is executed once before the loop has begun. The second one contains a condition
that is checked at the beginning of every iteration the loop, and the third one an
instruction (or, again, a set of instructions separated by a comma) that is executed at
the end of every iteration. Therefore, the code above would be equivalent to writing
the following:
$i = 0;
while ($i < 10) {
echo $i . PHP_EOL;
$i++;
}
The built-in PHP _EOL constant represents the “end of line” marker for your current operating
system.
Licensed to 482634 - Amber Barrow (itsadmin@deakin.edu.au)
Similar to for is the foreach construct, which allows you to loop through an array;
we discuss this construct in the Arrays chapter.