PHP Data Types: Complete Beginner to Advanced Guide

Welcome to phponline.in, your trusted learning platform for mastering PHP programming. Understanding PHP data types is one of the first and most important steps in becoming a successful PHP developer. This detailed guide will take you from beginner-level concepts to more advanced nuances of handling data in PHP.

You will Learn

1. Introduction to PHP Data Types
2. Dynamic Typing in PHP
3. Scalar Data Types
   • String
   • Integer
   • Float (Double)
   • Boolean
4. Compound Data Types
   • Array
   • Object
   • Callable
   • Iterable
5. Special Data Types
   • NULL
   • Resource
6. Type Juggling in PHP
7. Type Casting in PHP
8. Strict vs Loose Typing
9. Using gettype() and var_dump()
10. Data Type Conversion Examples
11. Real-World Use Cases
12. Best Practices
13. PHP 8 Type Enhancements

1. Introduction to PHP Data Types

A data type in PHP defines the type of value a variable can hold. PHP supports a wide variety of data types, which makes it powerful and flexible. These include scalar types (such as integers and strings), compound types (like arrays and objects), and special types (like NULL and resource).

2. Dynamic Typing in PHP

PHP is a dynamically typed language. This means that you don’t need to declare data types explicitly. The PHP interpreter determines the data type of a variable at runtime based on the value assigned.

$name = "John";      // String
offset = 5;           // Integer
$price = 12.50;       // Float
$active = true;       // Boolean

3. Scalar Data Types

Scalar types are simple data types that represent a single value.

String

A string is a sequence of characters, usually enclosed in double or single quotes.

$name = "PHP Tutorial";
echo $name;

Integer

An integer is a whole number (positive or negative).

$count = 100;
echo $count;

Float (Double)

A float (or double) represents numbers with decimal points.

$price = 99.99;
echo $price;

Boolean

A boolean can be either true or false.

$loggedIn = true;

4. Compound Data Types

Compound types are used to hold multiple values.

Array

An array can store multiple values in one variable.

$languages = array("PHP", "JavaScript", "Python");
print_r($languages);

Object

An object is an instance of a class.

class Person {
    public $name = "John";
}

$obj = new Person();
echo $obj->name;

Callable

This type refers to functions or methods that can be called.

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

Iterable

Introduced in PHP 7.1, used in loops.

function printItems(iterable $items) {
    foreach ($items as $item) {
        echo $item;
    }
}

5. Special Data Types

NULL

A variable with no value assigned becomes NULL.

$empty = NULL;

Resource

Used to hold references to external resources like database connections.

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

6. Type Juggling in PHP

PHP automatically converts data from one type to another depending on the context.

$sum = "10" + 5; // Result: 15 (integer)

7. Type Casting in PHP

You can manually convert types using type casting.

$number = "50";
$intNumber = (int) $number;

8. Strict vs Loose Typing

Loose Typing (Default)

PHP allows flexible type handling.

function add($a, $b) {
    return $a + $b;
}

Strict Typing

Introduced with PHP 7.

declare(strict_types=1);
function add(int $a, int $b): int {
    return $a + $b;
}

9. Using gettype() and var_dump()

• gettype() returns the data type of a variable.

gettype("Hello"); // Returns: string

• var_dump() displays the type and value.

var_dump(100.5);

10. Data Type Conversion Examples

$stringNumber = "200";
$converted = (int)$stringNumber; // 200 as integer

$boolean = (bool) 1; // true

11. Real-World Use Cases

• Store user credentials in strings
• Use booleans for toggling features
• Float for storing prices
• Objects for complex data like users or products

12. Best Practices

• Always initialize variables
• Use type casting when necessary
• Validate data types during input handling
• Avoid relying too much on type juggling

13. PHP 8 Type Enhancements

PHP 8 introduced new features for better type handling:

• Union Types: function foo(int|string $param)
• Mixed Type
• Static Return Type
• Constructor Property Promotion

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Read this

• PHP Variables Overview
• PHP Operators
• PHP Functions
• PHP Arrays
• PHP OOP Concepts

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