PHP
5 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;
?>
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);
?>
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:
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.
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