Tutorials References Menu

PHP Tutorial

PHP HOME PHP Intro PHP Install PHP Syntax PHP Comments PHP Variables PHP Echo / Print PHP Data Types PHP Strings PHP Numbers PHP Math PHP Constants PHP Operators PHP If...Else...Elseif PHP Switch PHP Loops PHP Functions PHP Arrays PHP Superglobals PHP RegEx

PHP Forms

PHP Form Handling PHP Form Validation PHP Form Required PHP Form URL/E-mail PHP Form Complete

PHP Advanced

PHP Date and Time PHP Include PHP File Handling PHP File Open/Read PHP File Create/Write PHP File Upload PHP Cookies PHP Sessions PHP Filters PHP Filters Advanced PHP Callback Functions PHP JSON PHP Exceptions

PHP OOP

PHP What is OOP PHP Classes/Objects PHP Constructor PHP Destructor PHP Access Modifiers PHP Inheritance PHP Constants PHP Abstract Classes PHP Interfaces PHP Traits PHP Static Methods PHP Static Properties PHP Namespaces PHP Iterables

MySQL Database

MySQL Database MySQL Connect MySQL Create DB MySQL Create Table MySQL Insert Data MySQL Get Last ID MySQL Insert Multiple MySQL Prepared MySQL Select Data MySQL Where MySQL Order By MySQL Delete Data MySQL Update Data MySQL Limit Data

PHP XML

PHP XML Parsers PHP SimpleXML Parser PHP SimpleXML - Get PHP XML Expat PHP XML DOM

PHP - AJAX

AJAX Intro AJAX PHP AJAX Database AJAX XML AJAX Live Search AJAX Poll

PHP Examples

PHP Examples PHP Compiler

PHP Reference

PHP Overview PHP Array PHP Calendar PHP Date PHP Directory PHP Error PHP Exception PHP Filesystem PHP Filter PHP FTP PHP JSON PHP Keywords PHP Libxml PHP Mail PHP Math PHP Misc PHP MySQLi PHP Network PHP Output Control PHP RegEx PHP SimpleXML PHP Stream PHP String PHP Variable Handling PHP XML Parser PHP Zip PHP Timezones

PHP Data Types


PHP Data Types

Variables can store data of different types, and different data types can do different things.

PHP supports the following data types:

  • String
  • Integer
  • Float (floating point numbers - also called double)
  • Boolean
  • Array
  • Object
  • NULL
  • Resource

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

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

echo $x;
echo "<br>";
echo $y;
?>
Try it Yourself »

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

<?php
$x = 5985;
var_dump($x);
?>
Try it Yourself »


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

<?php
$x = 10.365;
var_dump($x);
?>
Try it Yourself »

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

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

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 the properties.

If you create a __construct() function, PHP will automatically call this function when you create an object from a class.

Example

<?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();
?>
Try it Yourself »

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

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

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.