A.4. Chapter 4

Solution to Question 4-1

Code that performs a task.

Solution to Question 4-2

An operator.

Solution to Question 4-3

An operator combines simple expressions into more complex expressions. It does so by creating relationships between the simple expressions that can then be evaluated.

Solution to Question 4-4

An operator.

Solution to Question 4-5

An operator that combines two expressions into a more complex single expression.

Solution to Question 4-6

An operator that takes three operands.

Solution to Question 4-7

No—they take only numbers.

Solution to Question 4-8

It's an array, integer, or string.

Solution to Question 4-9

Yes—you'll end up with the wrong operator.

Solution to Question 4-10

It checks whether a variable is set.

Solution to Question 4-11

The switch statement is written as follows:

switch ($action) {
  case "add":
    $x = $x+y;
    break;
  case "subtract":
    $x = $x-y;
    break;
  case "multiply":
    $x = $x*$y;
    break;
  case "divide":
    $x = $x/$y;
    break;
}

Solution to Question 4-12

It tells PHP not to execute cases other than the matching case.

Solution to Question 4-13

The loop is written as follows:

<?php
for ($num = 10; $num >= 1; $num&#8722;&#8722;) {
    print "$num<br>";
}
?>