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
• String
• 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:

< ?php 
$x = class="phpstringcolor" style="color:brown">"Hello world!";
$y = class="phpstringcolor" style="color:brown">'Hello world!';

class="phpkeywordcolor" style="color:mediumblue">echo $x;
class="phpkeywordcolor" style="color:mediumblue">echo class="phpstringcolor" style="color:brown">"< br>"; 
class="phpkeywordcolor" style="color:mediumblue">echo $y;
class="phptagcolor" style="color:red">?>

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:

< ?php 
$x = class="phpnumbercolor" style="color:red">5985;
var_dump($x);
class="phptagcolor" style="color:red">?>

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:

< ?php 
$x = class="phpnumbercolor" style="color:red">10.365;
var_dump($x);
class="phptagcolor" style="color:red">?>

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:

< ?php 
$cars = class="phpkeywordcolor" style="color:mediumblue">array(class="phpstringcolor" style="color:brown">"Volvo",class="phpstringcolor"
style="color:brown">"BMW",class="phpstringcolor" style="color:brown">"Toyota");
var_dump($cars);
class="phpnumbercolor" style="color:red"> class="phptagcolor" style="color:red">?>

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

PHP Object

An object is a data type which stores data and information on how to process that data.

In PHP, an object must be explicitly declared.

First we must declare a class of object. For this, we use the class keyword. A class is a structure that can contain properties and methods:

< ?php
class="phpkeywordcolor" style="color:mediumblue">class Car {
  class="phpkeywordcolor" style="color:mediumblue">function Car() {
    $this->model = class="phpstringcolor" style="color:brown">"VW";
class="phpnumbercolor" style="color:red">   }
}

class="commentcolor" style="color:green">// create an object
class="phpnumbercolor" style="color:red"> $herbie = class="phpkeywordcolor" style="color:mediumblue">new Car();

class="commentcolor" style="color:green">// show object properties
class="phpkeywordcolor" style="color:mediumblue">echo $herbie->model;
class="phptagcolor" style="color:red">?>

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:

< ?php
$x = class="phpstringcolor" style="color:brown">"Hello world!";
$x = null;
var_dump($x);
class="phptagcolor" style="color:red">?>

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.