PHP Data Types

PHP data types describe what kind of value a variable holds. PHP decides the type automatically, but knowing the types helps you avoid bugs and write typed functions in PHP 8.

The Main PHP Data Types

• string: text like "hello"
• int: whole numbers like 42 or -7
• float: decimals like 3.14
• bool: true or false
• array: an ordered map of values
• object: an instance of a class
• null: no value
• Enums (PHP 8.1+): a fixed set of named cases

Inspecting Types With var_dump

var_dump() prints the type and value. It is the most useful debugging tool for beginners.

<?php
var_dump("PHP");
var_dump(8);
var_dump(8.3);
var_dump(true);
var_dump(null);
var_dump([1, 2]);

string(3) "PHP"
int(8)
float(8.3)
bool(true)
NULL
array(2) {
  [0]=>
  int(1)
  [1]=>
  int(2)
}

Type Casting

You can convert a value to another type by putting the type in parentheses. Functions like intval() do the same thing.

<?php
$input = "42 apples";
$n = (int) $input;
echo gettype($n), " ", $n, "\n";
echo (string) 3.5 . "\n";
var_dump((bool) "");
var_dump((bool) "0");

integer 42
3.5
bool(false)
bool(false)

Falsy Values

When converted to bool, these values become false: false, 0, 0.0, "", "0", an empty array and null. Everything else is true. This matters a lot in if statements.

PHP Enums

Enums let you define a type with a limited set of values, perfect for statuses. Backed enums carry a string or int value.

<?php
enum Status: string {
    case Draft = 'draft';
    case Published = 'published';
}

$s = Status::from('published');
echo $s->name . " => " . $s->value;

Published => published

Frequently asked questions

How do I check the type of a variable in PHP?

Use gettype() for a name, get_debug_type() for a modern readable name, or functions like is_int(), is_string() and is_array() for checks.

Is PHP strongly typed?

PHP is dynamically typed, but PHP 8 supports type declarations and strict_types mode, so you can make it behave much like a strongly typed language.

What is the difference between null and an empty string?

null means no value at all, while "" is a string with zero characters. Both are falsy, but is_null() is only true for null.