2.1 PHP Data Types

PHP String

• A string is a sequence of characters, like "Hello world!".
• A string can be any text inside quotes. You can use single or double quotes:

Example 1: PHP String

<?php
$x = "Hello world!";
$y = 'Hello world!';

echo $x;
echo "<br>";
echo $y;
?>

PHP Integer

• An integer data type is a non-decimal number between -2,147,483,648 and 2,147,483,647.
• Rules for integers:
  • An integer must have at least one digit
  • An integer must not have a decimal point
  • An integer can be either positive or negative
  • Integers can be specified in: decimal (base 10), hexadecimal (base 16), octal (base 8), or binary (base 2) notation
• In the following example $x is an integer. The PHP var_dump() function returns the data type and value

Example 2: PHP Integer

<?php
$x = 5985;
var_dump($x);
?>

PHP Float

• A float (floating point number) is a number with a decimal point or a number in exponential form.
• In the following example $x is a float. The PHP var_dump() function returns the data type and value:

Example 3: PHP Float

<?php
$x = 10.365;
var_dump($x);
?>

PHP Boolean

A Boolean represents two possible states: TRUE or FALSE.

$x = true;
$y = false;

Booleans are often used in conditional testing. You will learn more about conditional testing in a later chapter of this tutorial.

PHP Array

• An array stores multiple values in one single variable.
• In the following example $cars is an array. The PHP var_dump() function returns the data type and value

Example 4: PHP Array

<?php
$cars = array("Volvo","BMW","Toyota");
var_dump($cars);
?>

You will learn a lot more about arrays in later chapters of this tutorial.

PHP Object

• Classes and objects are the two main aspects of object-oriented programming.
• A class is a template for objects, and an object is an instance of a class.
• When the individual objects are created, they inherit all the properties and behaviors from the class, but each object will have different values for the properties.
• Let's assume we have a class named Car. A Car can have properties like model, color, etc. We can define variables like $model, $color, and so on, to hold the values of these properties.
• When the individual objects (Volvo, BMW, Toyota, etc.) are created, they inherit all the properties and behaviors from the class, but each object will have different values for their properties.
• If you create a __construct() function, PHP will automatically call this function when you create an object from a class.

Example 5: PHP Object

<?php
class Car {
  public $color;
  public $model;
  public function __construct($color, $model) {
    $this->color = $color;
    $this->model = $model;
  }
  public function message() {
    return "My car is a " . $this->color . " " . $this->model . "!";
  }
}

$myCar = new Car("black", "Volvo");
echo $myCar -> message();
echo "<br>";
$myCar = new Car("red", "Toyota");
echo $myCar -> message();
?>

PHP NULL Value

• Null is a special data type which can have only one value: NULL.
• A variable of data type NULL is a variable that has no value assigned to it.
• Tip: If a variable is created without a value, it is automatically assigned a value of NULL.
• Variables can also be emptied by setting the value to NULL:

Example 6: PHP NULL Value

<?php
$x = "Hello world!";
$x = null;
var_dump($x);
?>

PHP Resource

• The special resource type is not an actual data type. It is the storing of a reference to functions and resources external to PHP.
• A common example of using the resource data type is a database call.
• We will not talk about the resource type here, since it is an advanced topic.