Data Types in PHP


Datatypes:

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;

?>

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 three formats: decimal (10-based), hexadecimal (16-based - prefixed with 0x) or octal (8-based - prefixed with 0)

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);

?>

Output:

int(5985)

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);

?>

Output:

float(10.365)

PHP Boolean

A Boolean represents two possible states: TRUE or FALSE.

$x = true;

$y = false;

Booleans are often used in conditional testing.

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);

?>

Output:

array(3) { [0]=> string(5) "Volvo" [1]=> string(3) "BMW" [2]=> string(6) "Toyota" }

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:

Example

<?php

class Car {

   function Car() {

       $this->model = "VW";

   }}

// create an object

$herbie = new Car();

// show object properties

echo $herbie->model;

?>

Output:

VW

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.

Example

<?php

$x = "Hello world!"; $x = null;

var_dump($x);

?>

Output:NULL

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.

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