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If you look at the world around you, you’ll find many examples of tangible objects: lamps, phones, computers, and cars. Also, you can find intangible objects such as bank accounts and transactions.
All of these objects share the two common key characteristics:
For example, a bank account has the state that consists of:
A bank account also has the following behaviors:
PHP objects are conceptually similar to real-world objects because they consist of state and behavior.
An object holds its state in variables that are often referred to as properties. An object also exposes its behavior via functions which are known as methods.
Example: Type object
<?php
$someObject = (object) [
'some_key' => 'some value',
'other key' => 1024,
10 => true,
];
class SomeClass
{
public $publicProperty;
protected $protectedProperty = 15.5;
private $privateProperty = 'hello';
}
$otherObject = new SomeClass();
print("Information:\n");
var_dump($someObject);
print('Type: ' . gettype($someObject) . PHP_EOL . PHP_EOL);
print("Information:\n");
var_dump($otherObject);
print('Type: ' . gettype($otherObject) . PHP_EOL . PHP_EOL);
Result (PHP 8.4):
Information:
object(stdClass)#1 (3) {
["some_key"]=>
string(10) "some value"
["other key"]=>
int(1024)
["10"]=>
bool(true)
}
Type: object
Information:
object(SomeClass)#2 (3) {
["publicProperty"]=>
NULL
["protectedProperty":protected]=>
float(15.5)
["privateProperty":"SomeClass":private]=>
string(5) "hello"
}
Type: object
Source code: Example
To create a new object, use the new statement to instantiate a class:
Example: Object construction
<?php
class foo
{
function do_foo()
{
echo "Doing foo.";
}
}
$bar = new foo;
$bar->do_foo();
?>
[That’s can be also done by casting an array to the object like (object) ['nickname' => 'katheroine', 'occupy' => 'programmer'] – KK]
Example: Object definition and initialisation
<?php
$objectFromEmptyArray = (object) [];
print("Defined from empty array:\n\n");
print_r($objectFromEmptyArray);
print(PHP_EOL);
$objectFromIndexedArray = (object) [null, true, 3, 'orange'];
print("Defined from indexed array:\n\n");
print_r($objectFromIndexedArray);
print(PHP_EOL);
$objectFromAssociativeArray = (object) [
'some_key' => 'some value',
'other key' => 1024,
10 => true,
];
print("Defined from associative array:\n\n");
print_r($objectFromAssociativeArray);
print(PHP_EOL);
$objectFromStdClass = new stdClass();
print("Defined from stdClass class:\n\n");
print_r($objectFromStdClass);
print(PHP_EOL);
class SomeClass
{
public $publicProperty;
protected $protectedProperty;
private $privateProperty;
}
$uninitialisedObjectFromClass = new SomeClass();
print("Not initialised, defined from class:\n\n");
print_r($uninitialisedObjectFromClass);
print(PHP_EOL);
class OtherClass
{
function __construct(
public $publicProperty,
protected $protectedProperty,
private $privateProperty
) {
}
}
$initialisedObjectFromClass = new OtherClass(16, 14.2, 'welcome');
print("Initialised, defined from class:\n\n");
print_r($uninitialisedObjectFromClass);
print(PHP_EOL);
Result (PHP 8.4):
Defined from empty array:
stdClass Object
(
)
Defined from indexed array:
stdClass Object
(
[0] =>
[1] => 1
[2] => 3
[3] => orange
)
Defined from associative array:
stdClass Object
(
[some_key] => some value
[other key] => 1024
[10] => 1
)
Defined from stdClass class:
stdClass Object
(
)
Not initialised, defined from class:
SomeClass Object
(
[publicProperty] =>
[protectedProperty:protected] =>
[privateProperty:SomeClass:private] =>
)
Initialised, defined from class:
SomeClass Object
(
[publicProperty] =>
[protectedProperty:protected] =>
[privateProperty:SomeClass:private] =>
)
Source code: Example
Example: Object assignment and overwriting
<?php
class SomeClass
{
function __construct(
public $publicProperty = null,
protected $protectedProperty = 15.5,
private $privateProperty = 'hello'
) {
}
}
$someObject = new SomeClass();
print("Initialised and assigned:\n\n");
print_r($someObject);
print(PHP_EOL);
$someObject = new SomeClass(16, 14.2, 'welcome');
print("Overwritten:\n\n");
print_r($someObject);
print(PHP_EOL);
$someObject->publicProperty = 'hello';
print("After overwriting a property:\n\n");
print_r($someObject);
print(PHP_EOL);
$someObject->dynamicProperty = 10;
print("After dynamically added a property:\n\n");
print_r($someObject);
print(PHP_EOL);
Result (PHP 8.4):
Initialised and assigned:
SomeClass Object
(
[publicProperty] =>
[protectedProperty:protected] => 15.5
[privateProperty:SomeClass:private] => hello
)
Overwritten:
SomeClass Object
(
[publicProperty] => 16
[protectedProperty:protected] => 14.2
[privateProperty:SomeClass:private] => welcome
)
After overwriting a property:
SomeClass Object
(
[publicProperty] => hello
[protectedProperty:protected] => 14.2
[privateProperty:SomeClass:private] => welcome
)
After dynamically added a property:
SomeClass Object
(
[publicProperty] => hello
[protectedProperty:protected] => 14.2
[privateProperty:SomeClass:private] => welcome
[dynamicProperty] => 10
)
Source code: Example
Example: Object creating
<?php
$objectFromIndexedArray = (object) [null, true, 3, 'orange'];
$objectFromAssociativeArray = (object) [
'some_key' => 'some value',
'other key' => 1024,
10 => true,
];
$objectFromStdClass = new stdClass();
class SomeClass
{
function __construct(
public $publicProperty,
protected $protectedProperty,
private $privateProperty = 1024
) {
}
}
$uninitialisedObjectFromClass = new SomeClass('hello', 15.5);
print("From indexed array:\n\n");
print_r($objectFromIndexedArray);
print(PHP_EOL);
print("From associative array:\n\n");
print_r($objectFromAssociativeArray);
print(PHP_EOL);
print("From stdClass class:\n\n");
print_r($objectFromStdClass);
print(PHP_EOL);
print("From defined class:\n\n");
print_r($uninitialisedObjectFromClass);
print(PHP_EOL);
Result (PHP 8.4):
From indexed array:
stdClass Object
(
[0] =>
[1] => 1
[2] => 3
[3] => orange
)
From associative array:
stdClass Object
(
[some_key] => some value
[other key] => 1024
[10] => 1
)
From stdClass class:
stdClass Object
(
)
From defined class:
SomeClass Object
(
[publicProperty] => hello
[protectedProperty:protected] => 15.5
[privateProperty:SomeClass:private] => 1024
)
Source code: Example
Example: Object displaying
<?php
class SomeClass
{
function __construct(
public $publicProperty,
protected $protectedProperty,
private $privateProperty = 1024
) {
}
}
$someObject = new SomeClass('hello', 15.5);
print("Some object:\n\n");
var_dump($someObject);
print(PHP_EOL);
print_r($someObject);
print(PHP_EOL);
Result (PHP 8.4):
Some object:
object(SomeClass)#1 (3) {
["publicProperty"]=>
string(5) "hello"
["protectedProperty":protected]=>
float(15.5)
["privateProperty":"SomeClass":private]=>
int(1024)
}
SomeClass Object
(
[publicProperty] => hello
[protectedProperty:protected] => 15.5
[privateProperty:SomeClass:private] => 1024
)
Source code: Example
Example: Object modifying
<?php
class SomeClass
{
function __construct(
public $publicProperty,
protected $protectedProperty,
private $privateProperty = 10
) {
}
public function setProtectedProperty($protectedProperty)
{
$this->protectedProperty = $protectedProperty;
}
public function setPrivateProperty($privateProperty)
{
$this->privateProperty = $privateProperty;
}
}
$someObject = new SomeClass('some value', 15.5);
print_r($someObject);
print(PHP_EOL);
$someObject->publicProperty = 'hello';
$someObject->setProtectedProperty(0.2);
$someObject->setPrivateProperty(1024);
print_r($someObject);
print(PHP_EOL);
$someObject->someDynamicProperty = '16';
$someObject->otherDynamicProperty = 'coffee';
print_r($someObject);
print(PHP_EOL);
Result (PHP 8.4):
SomeClass Object
(
[publicProperty] => some value
[protectedProperty:protected] => 15.5
[privateProperty:SomeClass:private] => 10
)
SomeClass Object
(
[publicProperty] => hello
[protectedProperty:protected] => 0.2
[privateProperty:SomeClass:private] => 1024
)
SomeClass Object
(
[publicProperty] => hello
[protectedProperty:protected] => 0.2
[privateProperty:SomeClass:private] => 1024
[someDynamicProperty] => 16
[otherDynamicProperty] => coffee
)
Source code: Example
Example: Object destroying
<?php
$someObject = (object) [
'someField' => 'some value',
'otherField' => 1024
];
var_dump(isset($someObject));
var_dump($someObject);
print(PHP_EOL);
unset($someObject);
var_dump(isset($someObject));
print(PHP_EOL);
Result (PHP 8.4):
bool(true)
object(stdClass)#1 (2) {
["someField"]=>
string(10) "some value"
["otherField"]=>
int(1024)
}
bool(false)
Source code: Example
Example: Object properties
<?php
class Data
{
public $programmingLanguage;
public $database;
protected $operatingSystem = 'Unix';
private $id;
public function __construct($id)
{
$this->id = $id;
}
public function getId()
{
return $this->id;
}
public function setOperatingSystem($operatingSystem)
{
$this->operatingSystem = $operatingSystem;
}
public function getOperatingSystem()
{
return $this->operatingSystem;
}
}
$data = new Data(1024);
$data->setOperatingSystem('Linux');
$data->database = 'MongoDB';
$data->programmingLanguage = 'PHP';
print("Data:\n\n");
var_dump($data);
print(PHP_EOL);
print("id: {$data->getId()}\n");
print("operating system: {$data->getOperatingSystem()}\n");
print("database: {$data->database}\n");
print("programming language: {$data->programmingLanguage}\n\n");
Result (PHP 8.4):
Data:
object(Data)#1 (4) {
["programmingLanguage"]=>
string(3) "PHP"
["database"]=>
string(7) "MongoDB"
["operatingSystem":protected]=>
string(5) "Linux"
["id":"Data":private]=>
int(1024)
}
id: 1024
operating system: Linux
database: MongoDB
programming language: PHP
Source code: Example
Example: Object properties defining and initialising
<?php
$someObjectFromArray = (object) [
'some_key' => 'some value',
'other key' => 1024,
10 => true,
];
print("From array:\n\n");
var_dump($someObjectFromArray);
print(PHP_EOL);
class SomeClass
{
public $publicProperty;
protected $protectedProperty = 16;
private $somePrivateProperty;
public function __construct(private $otherPrivateProperty = 'hello')
{
$this->somePrivateProperty = 64.5;
}
}
$someObjectFromClass = new SomeClass();
print("From class without constructor argument:\n\n");
var_dump($someObjectFromClass);
print(PHP_EOL);
class OtherClass
{
public bool $publicProperty;
protected int $protectedProperty = 16;
private float $somePrivateProperty;
public function __construct(private string $otherPrivateProperty = 'hello')
{
$this->somePrivateProperty = 64.5;
}
}
$otherObjectFromClass = new OtherClass(true);
print("From class with constructor argument:\n\n");
var_dump($otherObjectFromClass);
print(PHP_EOL);
Result (PHP 8.4):
From array:
object(stdClass)#1 (3) {
["some_key"]=>
string(10) "some value"
["other key"]=>
int(1024)
["10"]=>
bool(true)
}
From class without constructor argument:
object(SomeClass)#2 (4) {
["publicProperty"]=>
NULL
["protectedProperty":protected]=>
int(16)
["somePrivateProperty":"SomeClass":private]=>
float(64.5)
["otherPrivateProperty":"SomeClass":private]=>
string(5) "hello"
}
From class with constructor argument:
object(OtherClass)#3 (3) {
["publicProperty"]=>
uninitialized(bool)
["protectedProperty":protected]=>
int(16)
["somePrivateProperty":"OtherClass":private]=>
float(64.5)
["otherPrivateProperty":"OtherClass":private]=>
string(1) "1"
}
Source code: Example
Example: Object dynamic properties
<?php
class SomeClass
{
public $someProperty = 1;
}
$someObject = new SomeClass();
print("Some object:\n\n");
print_r($someObject);
print(PHP_EOL);
$someObject->otherProperty = 2;
$someObject->anotherProperty = 3;
print_r($someObject);
print(PHP_EOL);
Result (PHP 8.4):
Some object:
SomeClass Object
(
[someProperty] => 1
)
SomeClass Object
(
[someProperty] => 1
[otherProperty] => 2
[anotherProperty] => 3
)
Source code: Example
Example: Object properties accessing
<?php
$someObjectFromArray = (object)[
'some_key' => 'some value',
'other key' => 1024,
10 => 10.5,
];
print("From array:\n\n");
print("some_key: {$someObjectFromArray->some_key}\n");
print("other key: {$someObjectFromArray->{'other key'}}\n");
print("other key: {$someObjectFromArray->{10}}\n\n");
class SomeClass
{
public $publicProperty;
protected $protectedProperty = 16;
private $privateProperty = 'hello';
public function getProtectedProperty()
{
return $this->protectedProperty;
}
public function getPrivateProperty()
{
return $this->privateProperty;
}
}
$someObjectFromClass = new SomeClass();
print("From class:\n\n");
print("publicProperty: {$someObjectFromClass->publicProperty}\n");
print("protectedProperty: {$someObjectFromClass->getProtectedProperty()}\n");
print("privateProperty: {$someObjectFromClass->getPrivateProperty()}\n\n");
Result (PHP 8.4):
From array:
some_key: some value
other key: 1024
other key: 10.5
From class:
publicProperty:
protectedProperty: 16
privateProperty: hello
Source code: Example
Example: Object properties updating
<?php
class SomeClass
{
public $publicProperty;
protected $protectedProperty = 16;
private $privateProperty = 'hello';
public function setProtectedProperty($protectedProperty)
{
$this->protectedProperty = $protectedProperty;
}
public function setPrivateProperty($privateProperty)
{
$this->privateProperty = $privateProperty;
}
}
$someObject = new SomeClass();
print("Some object:\n\n");
var_dump($someObject);
print(PHP_EOL);
$someObject->publicProperty = 2.5;
$someObject->setProtectedProperty(32);
$someObject->setPrivateProperty('hi');
var_dump($someObject);
print(PHP_EOL);
$someReference = $someObject;
$someReference->publicProperty = 100;
$someReference->setProtectedProperty(300);
$someReference->setPrivateProperty('welcome');
var_dump($someObject);
print(PHP_EOL);
Result (PHP 8.4):
Some object:
object(SomeClass)#1 (3) {
["publicProperty"]=>
NULL
["protectedProperty":protected]=>
int(16)
["privateProperty":"SomeClass":private]=>
string(5) "hello"
}
object(SomeClass)#1 (3) {
["publicProperty"]=>
float(2.5)
["protectedProperty":protected]=>
int(32)
["privateProperty":"SomeClass":private]=>
string(2) "hi"
}
object(SomeClass)#1 (3) {
["publicProperty"]=>
int(100)
["protectedProperty":protected]=>
int(300)
["privateProperty":"SomeClass":private]=>
string(7) "welcome"
}
Source code: Example
objectExample: Testing for object
<?php
$someObject = (object)[
'some_key' => 'some value',
'other key' => 1024,
10 => true,
];
print('Type of array object: ' . gettype($someObject) . PHP_EOL);
print('Is object? ' . (is_object($someObject) ? 'yes' : 'no') . PHP_EOL . PHP_EOL);
class SomeClass
{
public $publicProperty;
protected $protectedProperty = 15.5;
private $privateProperty = 'hello';
}
$otherObject = new SomeClass();
print('Type of class object: ' . gettype($otherObject) . PHP_EOL);
print('Is object? ' . (is_object($otherObject) ? 'yes' : 'no') . PHP_EOL . PHP_EOL);
$someNumber = 10;
print('Type of number: ' . gettype($someNumber) . PHP_EOL);
print('Is object? ' . (is_object($someNumber) ? 'yes' : 'no') . PHP_EOL . PHP_EOL);
Result (PHP 8.4):
Type of array object: object
Is object? yes
Type of class object: object
Is object? yes
Type of number: integer
Is object? no
Source code: Example
objectIf an object is converted to an object, it is not modified. If a value of any other type is converted to an object, a new instance of the stdClass built-in class is created. If the value was null, the new instance will be empty. An array converts to an object with properties named by keys and corresponding values. Note that in this case before PHP 7.2.0 numeric keys have been inaccessible unless iterated.
Example: Casting to an object
<?php
$obj = (object) array('1' => 'foo');
var_dump(isset($obj->{'1'})); // outputs 'bool(true)'
// Deprecated as of PHP 8.1
var_dump(key($obj)); // outputs 'string(1) "1"'
?>
For any other value, a member variable named scalar will contain the value.
Example: (object) cast
<?php
$obj = (object) 'ciao';
echo $obj->scalar; // outputs 'ciao'
?>
Example: Casting to object
<?php
$someNothing = null;
$nullToObject = (object) $someNothing;
print("null to object: ");
var_dump($nullToObject);
print(PHP_EOL);
$someRight = true;
$intToObject = (object) $someRight;
print("true to object: ");
var_dump($intToObject);
$someWrong = false;
$intToObject = (object) $someWrong;
print("false to object: ");
var_dump($intToObject);
print(PHP_EOL);
$someNumber = 0;
$intToObject = (object) $someNumber;
print("{$someNumber} to object: ");
var_dump($intToObject);
$someNumber = 3;
$intToObject = (object) $someNumber;
print("{$someNumber} to object: ");
var_dump($intToObject);
print(PHP_EOL);
$someMeasure = 3.5;
$floatToObject = (object) $someMeasure;
print("3.0 to object: ");
var_dump($floatToObject);
print(PHP_EOL);
$someText = "";
$stringToObject = (object) $someText;
print("\"{$someText}\" to object: ");
var_dump($stringToObject);
$someText = "hello";
$stringToObject = (object) $someText;
print("\"{$someText}\" to object: ");
var_dump($stringToObject);
print(PHP_EOL);
$someCollection = [];
$arrayToObject = (object) $someCollection;
print("[''] to object: ");
var_dump($arrayToObject);
$someCollection = [null, true, 2];
$arrayToObject = (object) $someCollection;
print("[null, true, 2] to object: ");
var_dump($arrayToObject);
$someCollection = [
'some_key' => 'some value',
'other key' => 1024,
10 => true,
];
$arrayToObject = (object) $someCollection;
print(<<<END
[
'some_key' => 'some value',
'other key' => 1024,
10 => true,
]
END . "\nto object: ");
var_dump($arrayToObject);
print(PHP_EOL);
Result (PHP 8.4):
null to object: object(stdClass)#1 (0) {
}
true to object: object(stdClass)#2 (1) {
["scalar"]=>
bool(true)
}
false to object: object(stdClass)#3 (1) {
["scalar"]=>
bool(false)
}
0 to object: object(stdClass)#2 (1) {
["scalar"]=>
int(0)
}
3 to object: object(stdClass)#3 (1) {
["scalar"]=>
int(3)
}
3.0 to object: object(stdClass)#2 (1) {
["scalar"]=>
float(3.5)
}
"" to object: object(stdClass)#4 (1) {
["scalar"]=>
string(0) ""
}
"hello" to object: object(stdClass)#5 (1) {
["scalar"]=>
string(5) "hello"
}
[''] to object: object(stdClass)#4 (0) {
}
[null, true, 2] to object: object(stdClass)#6 (3) {
["0"]=>
NULL
["1"]=>
bool(true)
["2"]=>
int(2)
}
[
'some_key' => 'some value',
'other key' => 1024,
10 => true,
]
to object: object(stdClass)#4 (3) {
["some_key"]=>
string(10) "some value"
["other key"]=>
int(1024)
["10"]=>
bool(true)
}
Source code: Example
objectExample: Casting from object
<?php
$emptyObject = (array)[];
$objectFromArray = (array)[
'some_key' => ' value',
'other key' => 1024,
10 => 14.2,
];
class SomeClass
{
public $publicProperty = 5;
protected $protectedProperty = 15.5;
private $privateProperty = 'hello';
}
$objectFromClass = new SomeClass();
$emptyObjectToBool = (bool) $emptyObject;
print("Empty object to bool: ");
var_dump($emptyObjectToBool);
$objectFromArrayToBool = (bool) $objectFromArray;
print("Object from array to bool: ");
var_dump($objectFromArrayToBool);
$objectFromClassToBool = (bool) $objectFromClass;
print("Object from class to bool: ");
var_dump($objectFromClassToBool);
print(PHP_EOL);
// $emptyObjectToInt = (int) $emptyObject;
// print("Empty object to int: ");
// var_dump($emptyObjectToInt);
// $objectFromArrayToInt = (int) $objectFromArray;
// print("Object from array to int: ");
// var_dump($objectFromArrayToInt);
// $objectFromClassToInt = (int) $objectFromClass;
// print("Object from class to int: ");
// var_dump($objectFromClassToInt);
// print(PHP_EOL);
// $emptyObjectToFloat = (float) $emptyObject;
// print("Empty object to float: ");
// var_dump($emptyObjectToFloat);
// $objectFromArrayToFloat = (float) $objectFromArray;
// print("Object from array to float: ");
// var_dump($objectFromArrayToFloat);
// $objectFromClassToFloat = (float) $objectFromClass;
// print("Object from class to float: ");
// var_dump($objectFromClassToFloat);
// print(PHP_EOL);
// $emptyObjectString = (string) $emptyObject;
// print("Empty object to string: ");
// var_dump($emptyObjectToString);
// $objectFromArrayToFloat = (string) $objectFromArray;
// print("Object from array to string: ");
// var_dump($objectFromArrayToFloat);
// $objectFromClassToFloat = (string) $objectFromClass;
// print("Object from class to string: ");
// var_dump($objectFromClassToFloat);
// print(PHP_EOL);
$emptyObjectToArray = (array) $emptyObject;
print("Empty object to object: ");
var_dump($emptyObjectToArray);
$objectFromArrayToArray = (array) $objectFromArray;
print("Object from array to object: ");
var_dump($objectFromArrayToArray);
$objectFromClassToArray = (array) $objectFromClass;
print("Object from class to object: ");
var_dump($objectFromClassToArray);
print(PHP_EOL);
Result (PHP 8.4):
Empty object to bool: bool(false)
Object from array to bool: bool(true)
Object from class to bool: bool(true)
Empty object to object: array(0) {
}
Object from array to object: array(3) {
["some_key"]=>
string(6) " value"
["other key"]=>
int(1024)
[10]=>
float(14.2)
}
Object from class to object: array(3) {
["publicProperty"]=>
int(5)
["*protectedProperty"]=>
float(15.5)
["SomeClassprivateProperty"]=>
string(5) "hello"
}
Source code: Example