PHP Data Types Explained: A Guide to Working with Variables

A boolean (or bool) is a data type that represents two possible values: true or false. Booleans are often used in conditional statements and control structures to determine whether a condition is met or not.

Example

<!DOCTYPE html>

<html>

<body>

<?php

$isTrue = true;

$isFalse = false;

if ($isTrue) {

echo gettype($isTrue)." ";

echo "This is true!";

} else {

echo gettype($isFalse)." ";

echo "This is false!";

}

</body>

</html>

Try it yourself

Note

The is_bool() function checks whether a variable is a boolean or not.
This function returns true (1) if the variable is a boolean, otherwise it returns false/nothing.

Integer

Integer means numeric data with a negative or positive sign. It holds only whole numbers, i.e., numbers without fractional part or decimal points.

Rules for integer:

An integer can be either positive or negative.
An integer must not contain decimal point.
Integer can be decimal (base 10), octal (base 8), or hexadecimal (base 16).
The range of an integer must be lie between 2,147,483,648 and 2,147,483,647 i.e., -2^31 to 2^31.

Example

<!DOCTYPE html>

<html>

<body>

<?php

$decimal = 42; // Decimal

$hex = 0x1A; // Hexadecimal (26 in decimal)

$octal = 0755; // Octal (493 in decimal)

$binary = 0b1010; // Binary (10 in decimal)

echo $decimal." ";

echo $hex." ";

echo $octal." ";

echo $binary." ";

</body>

</html>

Try it yourself

Float

A float (also known as a double or real number) is a data type that represents numbers with decimal points or numbers in scientific notation. Unlike integer, it can hold numbers with a fractional or decimal point, including a negative or positive sign.

Example

<!DOCTYPE html>

<html>

<body>

<?php

$price = 19.99; // A float representing a price

$discount = 0.15; // A float representing a 15% discount

$totalPrice = $price - ($price * $discount);

echo $totalPrice; // Outputs: 16.99 (the total price after discount)

</body>

</html>

Try it yourself

String

A string is a sequence of characters, used to store and manipulate text. Strings in PHP can include letters, numbers, symbols, or any combination of these.

String values must be enclosed either within single quotes or in double quotes. But both are treated differently.

Example

<!DOCTYPE html>

<html>

<body>

<?php

$name = "world";

$string1 = 'Hello, world!'; // Single-quoted string

$string2 = "Hello, $name!"; // Double-quoted string (variable parsing)

$string3 = 'Hello, $name!'; // Single-quoted string (variable parsing as string)

$string4 = 'Hello, '.$name; // Single-quoted string (variable parsing)

echo $string1." ";

echo $string2." ";

echo $string3." ";

echo $string4." ";

</body>

</html>

Try it yourself

Array

An array is a special variable that can hold multiple values at once. Arrays are one of the most powerful data types in PHP because they allow you to store and manipulate collections of values, whether they are numbers, strings, or even other arrays.

Example

<!DOCTYPE html>

<html>

<body>

<?php

$fruits = ["Apple", "Banana", "Cherry"];

echo $fruits[0]; // Outputs: Apple

echo $fruits[1]; // Outputs: Banana

</body>

</html>

Try it yourself

Objects

Objects are the instances of user-defined classes that can store both values and functions. They must be explicitly declared.

Example

<!DOCTYPE html>

<html>

<body>

<?php

class bike {

function model() {

$model_name = "Royal Enfield";

echo "Bike Model: " .$model_name;

}

$obj = new bike();

$obj -> model();

</body>

</html>

Try it yourself

Resources

Resources are not the exact data type in PHP. Basically, these are used to store some function calls or references to external PHP resources. For example - a database call. It is an external resource.

This is an advanced topic of PHP, so we will discuss it later in detail with examples.

NULL

NULL is a special data type that represents a variable with no value. It is used to indicate that a variable has been intentionally left empty or that a function or operation has no value to return. NULL is different from other data types like strings, integers, or arrays, and it is a unique value in PHP.

Example

<!DOCTYPE html>

<html>

<body>

<?php

$var = NULL; // Explicitly setting the variable to NULL

echo var_dump($var); // Outputs: NULL

</body>

</html>

Try it yourself

Note

If a variable is created without a value, it is automatically assigned a value of NULL.

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