Errata

Function names squares returns empty array when start is lower than stop.

TEST FAILURE

function testSquares()
{
$result = [4 => 16, 3 => 9, 2 => 4, 1 => 1];
$this->assertEquals($result, makeSquares(4,1));
}


function makeSquares($start=1, $stop=1)
{
$result = [];

foreach (squares($start, $stop) as $number => $square) {
$result[$number] = $square;
}

return $result;
}

function squares($start, $stop) {
if ($start < $stop) {
for ($i = $start; $i <= $stop; $i++) {
yield $i => $i * $i;
}
}
else {
for ($i = $stop (should be $start); $i >= $start (should be $stop); $i--) {
yield $i => $i * $i;
}
}
}
foreach (squares(3, 15) as $n => $square) {
printf("%d squared is %d\n", $n, $square);
}

Finding the maximum value using the arsort() function will NOT work since the array is not reindexed.
Therefore, the $array[0] value will not be the maximum with arsort($array);

Must use rsort($array) to get the maximum value in $array[0].

[Sorry - I typed the wrong page number. Not page 116 but page 118]

Finding the maximum value using the arsort() function will NOT work since the array is not reindexed.
Therefore, the $array[0] value will not be the maximum with arsort($array);

Must use rsort($array) to get the maximum value in $array[0].

"Using isset() is essential when assigning default values. Without it, the nondefault value can't be 0 or anything else that evaluates to false. Consider this assignment:

$cars = isset($_GET['cars']) ? $_GET['cars'] : $default_cars;

If $_GET['cars'] is 0, $cars is set to $default_cars even though 0 may be a valid value for $cars."

WRONG!!!! $cars in the above code will be set to 0 if $_GET['cars'] is 0!!!!

The example meant to say this:

"Consider this assignment:

$cars = $_GET['cars'] ? $_GET['cars'] : $default_cars;
[...]"

Because we see the author trying to make the point that using isset() is needed here to prevent the logic error in his example.

The class guest_book does not have $comments declared as an array. In fact, $comments is not declared at all.

My version of Php will not properly initialize the $comments array when

array_unshift($this->comments, $comment);

is executed in the class.

When I added:

public $comments = []; to the top of the class the code worked.

Book states:

"By default, PHP accepts a session identifier sent in a cookie, but if session.use_only_cookies is set to 1, it will accept a session identifier in the URL."

WRONG!!!!
If session.use_only_cookies is set to 0, it will accept a session id in the URL. If it is set to 1, it will only accept cookies!

The book has it exactly backwards.

The sentence reads "When you call mean(96,93,98,98), func_num_args() returns 3. The first argument is in position 0, so you iterate from 0 to 2, not 1 to 3."

There are four arguments passed in to the function, so it should read "When you call mean(96,93,98,98), func_num_args() returns 4. The first argument is in position 0, so you iterate from 0 to 3, not 1 to 4."