What is data type in php definition?

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
• 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

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

echo $x;
echo "
";
echo $y;
?>

Try it Yourself »

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 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 Boolean

A Boolean represents two possible states: TRUE or 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

$cars = array("Volvo","BMW","Toyota");
var_dump($cars);
?>

Try it Yourself »

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

PHP Object

Classes and objects are the two main aspects of object-oriented programming.

A class is a template for objects, and an object is an instance of a class.

When the individual objects are created, they inherit all the properties and behaviors from the class, but each object will have different values for the properties.

Let's assume we have a class named Car. A Car can have properties like model, color, etc. We can define variables like $model, $color, and so on, to hold the values of these properties.

When the individual objects (Volvo, BMW, Toyota, etc.) are created, they inherit all the properties and behaviors from the class, but each object will have different values for the properties.

If you create a __construct() function, PHP will automatically call this function when you create an object from a class.

Example

class Car {
  public $color;
  public $model;
  public function __construct($color, $model) {
    $this->color = $color;
    $this->model = $model;
  }
  public function message() {
    return "My car is a " . $this->color . " " . $this->model . "!";
  }
}

$myCar = new Car("black", "Volvo");
echo $myCar -> message();
echo "
";
$myCar = new Car("red", "Toyota");
echo $myCar -> message();
?>

Try it Yourself »

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 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.

In this tutorial you will learn about the data types available in PHP.

Data Types in PHP

The values assigned to a PHP variable may be of different data types including simple string and numeric types to more complex data types like arrays and objects.

PHP supports total eight primitive data types: Integer, Floating point number or Float, String, Booleans, Array, Object, resource and NULL. These data types are used to construct variables. Now let's discuss each one of them in detail.

PHP Integers

Integers are whole numbers, without a decimal point (..., -2, -1, 0, 1, 2, ...). Integers can be specified in decimal (base 10), hexadecimal (base 16 - prefixed with 0x) or octal (base 8 - prefixed with 0) notation, optionally preceded by a sign (- or +).

";
 
$b = -123; // a negative number
var_dump($b);
echo "
";
 
$c = 0x1A; // hexadecimal number
var_dump($c);
echo "
";
 
$d = 0123; // octal number
var_dump($d);
?>

Note: Since PHP 5.4+ you can also specify integers in binary (base 2) notation. To use binary notation precede the number with 0b (e.g. $var = 0b11111111;).

PHP Strings

Strings are sequences of characters, where every character is the same as a byte.

A string can hold letters, numbers, and special characters and it can be as large as up to 2GB (2147483647 bytes maximum). The simplest way to specify a string is to enclose it in single quotes (e.g. 'Hello world!'), however you can also use double quotes ("Hello world!").

";
 
$b = "Hello world!";
echo $b;
echo "
";
 
$c = 'Stay here, I\'ll be back.';
echo $c;
?>

You will learn more about strings in PHP Strings tutorial.

PHP Floating Point Numbers or Doubles

Floating point numbers (also known as "floats", "doubles", or "real numbers") are decimal or fractional numbers, like demonstrated in the example below.

";
 
$b = 10.2e3;
var_dump($b);
echo "
";
 
$c = 4E-10;
var_dump($c);
?>

PHP Booleans

Booleans are like a switch it has only two possible values either 1 (true) or 0 (false).

PHP Arrays

An array is a variable that can hold more than one value at a time. It is useful to aggregate a series of related items together, for example a set of country or city names.

An array is formally defined as an indexed collection of data values. Each index (also known as the key) of an array is unique and references a corresponding value.

";
 
$color_codes = array(
    "Red" => "#ff0000",
    "Green" => "#00ff00",
    "Blue" => "#0000ff"
);
var_dump($color_codes);
?>

You will learn more about arrays in PHP Array tutorial.

PHP Objects

An object is a data type that not only allows storing data but also information on, how to process that data. An object is a specific instance of a class which serve as templates for objects. Objects are created based on this template via the new keyword.

Every object has properties and methods corresponding to those of its parent class. Every object instance is completely independent, with its own properties and methods, and can thus be manipulated independently of other objects of the same class.

Here's a simple example of a class definition followed by the object creation.

str;
    }
}
 
// Create object from class
$message = new greeting;
var_dump($message);
?>

Tip: The data elements stored within an object are referred to as its properties and the information, or code which describing how to process the data is called the methods of the object.

PHP NULL

The special NULL value is used to represent empty variables in PHP. A variable of type NULL is a variable without any data. NULL is the only possible value of type null.

";
 
$b = "Hello World!";
$b = NULL;
var_dump($b);
?>

When a variable is created without a value in PHP like $var; it is automatically assigned a value of null. Many novice PHP developers mistakenly considered both $var1 = NULL; and $var2 = ""; are same, but this is not true. Both variables are different — the $var1 has null value while $var2 indicates no value assigned to it.

PHP Resources

A resource is a special variable, holding a reference to an external resource.

Resource variables typically hold special handlers to opened files and database connections.

";
 
// Connect to MySQL database server with default setting
$link = mysqli_connect("localhost", "root", "");
var_dump($link);
?>

What is data type definition?

What is data type with example?