Taking Advantage of the Server - Web Publishing with HTML and CSS - page 629

Returning Values
Optionally, your function can return a value, or more specifically, a variable . Here's a
simple example of a function:

function add($a = 0, $b = 0) {
return $a + $b;

}

The return keyword is used to indicate that the value of a variable should be returned to
the caller of a function. You could call the previous function like this:

$sum = add(2, 3); // $sum set to 5

A function can just as easily return an array. Here's an example:

function makeArray($a, $b) {
return array($a, $b);

}

$new_array = makeArray('one', 'two');

If you don't explicitly return a value from your function, PHP will return the result of the
last expression inside the function anyway. For example, suppose I wrote the add func-
tion like this:

function add($a = 0, $b = 0) {
$a + $b;

}

Because $a + $b is the last expression in the function, PHP will go ahead and return its
result. That's the case for logical expressions, too. Here's an example:

function negate($a) {
!$a;

}

negate(1); // returns false
negate(0); // returns true

Your function can also return the result of another function, whether it's built in or one
you wrote yourself. Here are a couple of examples:

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function add($a = 0, $b = 0) {
return $a + $b;

}