How to Create a PHP Class and Its Objects?

We have already discussed what are classes and objects in Object-Oriented Programming. Now we will see how to create PHP classes and their objects.

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In order to create a Class in PHP, you have to follow some naming conventions. These are not mandatory, but to write well-organized code using OOP, you have to implement the following conventions.

PHP class naming conventions

• Class names should always start with a capital letter. If a class name contains more than two words, use PascalCase. Example – fruit => Fruit, search user => SearchUser.
• The class name and the file name should be the same. For example, if a class name is Apple, then the file name should be Apple.php.

Create a PHP class

Using the class keyword you can create a Class in PHP.

You have to write the class keyword before the class name (The class name and class keyword are separated by a space.), and after the class name, add the curly braces {} where you will define the methods and properties of the class.

<?php
class ClassName{
    // Methods and Properties
}

Example of a PHP class

In the following code you can see that there is a PHP class named MyClass.

The class has a property called $name whose value is John, and there is a method called sayHello.

Now you can see that there is a public keyword before the property and the method. This is an access modifier. There are 3 types of access modifiers in PHP – public, private, and protected.

It is mandatory to add an access modifier before the property name. But If you not specify an access modifier before a method, then the default modifier (public) will be assumed for the method.

<?php
class MyClass{
    // This is a Property (Variable)
    public $name = 'John';

    // This is a Method (Function)
    public function sayHello(){
        echo 'Hello';
    }
}

PHP class Instance or Object

As we all know that, to access or use the properties and methods of a class you have to create an instance or object of the class.

So, using the new keyword you can create an instance or object of a class in PHP.

new ClassName();

// assigning an object to a variable
$var1 = new ClassName();

Object Operator ->

To access the properties and methods of an object you have to use the object operator (->).

<?php
class MyClass{
    // This is a Property (Variable)
    public $name = 'John';

    // This is a Method (Function)
    public function sayHello(){
        echo 'Hello';
    }
}

$object1 = new MyClass();

// Don't add $ sign before the property name
echo $object1->name;

// For new line
echo "\n";

$object1->sayHello();

John
Hello

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Multiple instances of a class in PHP

You can create multiple instances of a PHP class, and they are completely different from each other.

The following MyClass has a property called $name whose default value is John, and there is a showName method that displays the name.

You can also see that there are two instances of MyClass: $object1 and $object2 and they are absolutely different.

To understand that you can see we have changed the value of the $object1->name property to 'Rocky', but the $object2->name is still 'John', because they are different.

<?php
class MyClass{
    public $name = 'John';

    public function showName(){
        return $this->name."\n";
    }
}

$object1 = new MyClass();
$object2 = new MyClass();

$object1->name = 'Rocky';

echo "Object 1 - ".$object1->showName();
echo "Object 2 - ".$object2->showName();

Object 1 - Rocky
Object 2 - John