PHP - Data Types

Here’s a large block of code with examples for most data types. PHP is a dynamically typed language, meaning that you can assign values of different types to the same variable reference at different points in your control flow.

Note that var_dump() is used frequently in this example to show the variables of different types, as echo and print() are only capable of outputting strings, numbers, and booleans (where true is cast to 1 and false is cast to 0). var_dump() is great for debugging.

datatypes.php

<?php
# string
$x = "words";
var_dump($x);
# int
$x = 10;
var_dump($x);
# float
$x = 10.1;
var_dump($x);
# boolean
$x = true;
var_dump($x);
# array
$x = array("alice", "bob", "charlie");
var_dump($x);
# object
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 . "!\n";
  }
}

$myCar = new Car("red", "Volvo");
var_dump($myCar);
echo($myCar->message());
# null
$x = null;
var_dump($x);
?>

Output of php datatypes.php:

string(5) "words"
int(10)
float(10.1)
bool(true)
array(3) {
  [0]=>
  string(5) "alice"
  [1]=>
  string(3) "bob"
  [2]=>
  string(7) "charlie"
}
object(Car)#1 (2) {
  ["color"]=>
  string(3) "red"
  ["model"]=>
  string(5) "Volvo"
}
My car is a red Volvo!
NULL

Typecasting and Strings

If you want to type cast to a different type, this is the syntax:

<?php
$some_int = 5
$im_a_string_now = (string) $some_int
?>

If you want to concatenate (combine) strings, use the dot operator:

<?php
$combine = "hello" . " " . "world"
?>