PHP Datatypes

title: PHP Data Types

Data Types

Variables can store data of different types such as:

  • String (“Hello”)
  • Integer (5)
  • Float (also called double) (1.0)
  • Boolean ( 1 or 0 )
  • Array ( array(“I”, “am”, “an”, “array”) )
  • Object
  • NULL
  • Resource


A string is a sequence of characters. It can be any text inside quotes (single or double):


$x = "Hello!"; $y = 'Hello!';


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)


$x = 5;


A float (floating point number) is a number with a decimal point or a number in exponential form.


$x = 5.01;


A Boolean represents two possible states: TRUE or FALSE. Booleans are often used in conditional testing.

$x = true; $y = false;


An array stores multiple values in one single variable.

$colours = array("Blue","Purple","Pink");

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.
Variables can also be emptied by setting the value to NULL.

Note: If a variable is created without a value, it is automatically assigned a value of NULL.

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



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. A class is a structure that can contain properties and methods.


<?php class Car { function Car() { $this->model = "VW"; } } // create an object $herbie = new Car(); // show object properties echo $herbie->model; ?>

You can also use a predefined generic empty class stdClass. It’s usefull for anonymous objects, dynamic properties or casting other types to object.

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