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MbarekTheEagle
MbarekTheEagle

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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

Getting the Data Type
You can get the data type of any object by using the var_dump() function.

Example
The var_dump() function returns the data type and the value:

$x = 5;
var_dump($x);
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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!';

var_dump($x);
echo "<br>";
var_dump($y);
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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:

Example

$x = 5985;
var_dump($x);
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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

$x = 10.365;
var_dump($x);
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PHP Boolean
A Boolean represents two possible states: TRUE or FALSE.

Example

$x = true;
var_dump($x);
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Booleans are often used in conditional testing.

You will learn more about conditional testing in the PHP If...Else chapter.

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);
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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 that 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 . "!";
  }
}

$myCar = new Car("red", "Volvo");
var_dump($myCar);
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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

$x = "Hello world!";
$x = null;
var_dump($x);
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Change Data Type
If you assign an integer value to a variable, the type will automatically be an integer.

If you assign a string to the same variable, the type will change to a string:

Example

$x = 5;
var_dump($x);

$x = "Hello";
var_dump($x);
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Top comments (1)

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sana_farsi_3ad21904f6f9c5 profile image
Sana Farsi • • Edited

To get data type for a variable you can also use gettype() function.
This function returns only data type of the passed variable and does not return its value.
Note that when we create a variable without a value it will throw a Warning: Undefined variable
and will automatically assign a value of NULL.
Another way to cast datatype is to use this statement:
$variable=(data_type)$variable;
or by using settype()function:
settype($variable,"data_type");
this will be more efficent because in some cases you may not know the value that you want to assign to the variable.