< Php Tutorial

Php data types

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PHP has a total of eight data types which we use to construct our variables .

  • Integers : are whole numbers, without a decimal point, like 4195.
  • Doubles : are floating-point numbers, like 3.14159 or 49.1.
  • Booleans : have only two possible values either true or false.
  • NULL : is a special type that only has one value: NULL.
  • Strings : are sequences of characters, like 'PHP supports string operations.'
  • Arrays : are named and indexed collections of other values.
  • Objects : are instances of programmer-defined classes, which can package up both other kinds of values and functions that are specific to the class.
  • Resources : are special variables that hold references to resources external to PHP (such as database connections).

The first five are simple types, and the next two (arrays and objects) are compound - the compound types can package up other arbitrary values of arbitrary type, whereas the simple types cannot. We will explain only simple data type in this chapters. Array and Objects will be explained separately.  


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); 
?>

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); 
?>

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); 
?>

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; 
?>

You will learn more about objects in a later chapter of this tutorial.


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); 
?>

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.

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