In PHP, a data type is a classification of data that tells the interpreter how the programmer intends to use the data. PHP is a loosely typed language, meaning you don't have to explicitly declare data types for variables. PHP automatically converts the variable to the correct data type based on its value.

Main Data Types in PHP

1. String

A string is a sequence of characters enclosed in single quotes (') or double quotes (").

$name = "John Doe";

2. Integer

An integer is a non-decimal number between -2,147,483,648 and 2,147,483,647.

$age = 30;

3. Float (Double)

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

$price = 10.99;

4. Boolean

A boolean represents two possible states: TRUE or FALSE.

$is_active = true;

5. Array

An array is a collection of values that can be of different data types. Arrays can be indexed or associative.

$colors = array("red", "green", "blue");

6. Object

An object is an instance of a class. Classes are used to structure data and methods in PHP.


class Car {
    function Car() {
        $this->model = "Tesla";
    }
}
$myCar = new Car();

7. NULL

The NULL data type represents a variable with no value. A variable of type NULL is one that has been assigned the constant NULL.

$var = NULL;

8. Resource

A resource is a special variable, holding a reference to an external resource like a database connection, file handling, etc.

$file = fopen("file.txt", "r");

9. Callable

A callable is a special type of variable that can be called as a function, such as an anonymous function or a method within an object.


function sayHello() {
    echo "Hello!";
}
$greet = 'sayHello';
$greet();

Type Juggling and Type Casting

Type Juggling

PHP automatically converts variables to the correct data type as needed.


$num = "10";
$sum = $num + 20;  // $num is automatically cast to an integer

Type Casting

You can explicitly convert a variable to a specific data type.

$var = (int)"100";  // $var is now an integer

Understanding data types in PHP is essential for effective coding, as it helps you manage data correctly and avoid errors related to type mismatches.

Datatype Introduction