How to Use Interfaces in PHP - Understanding PHP Interfaces With Practical Example

---

What is an Interface in PHP?

An interface in PHP is a contract that specifies what methods a class must implement. Interfaces are crucial in object-oriented programming as they allow for the creation of code that specifies which methods a class should implement, without having to define how these methods are handled.

Interfaces ensure a consistent API structure while allowing for flexibility in the implementation details. This is particularly useful in projects where multiple classes share the same structure but require different implementations.

Key Points About Interfaces:

• Interface methods do not have a body - they are only declared.
• Interface methods are public by default.
• All methods declared in an interface must be implemented by the class that uses the interface.

Practical Example: Implementing a BankAccount Interface

In our example, we'll define a BankAccount interface with three methods: deposit, withDraw, and getBalance. Then, we'll create a SavingAccount class that implements this interface.

<?php 

interface BankAccount{
    public function deposit($amount);
    public function withDraw($amount);
    public function getBalance();
}

class SavingAccount implements BankAccount{
    private $amount;
    private $name;

    public function __construct($amount, $name){
        $this->amount = $amount;
        $this->name = $name;
    }
   
    public function deposit($amount){
        $this->amount += $amount;
    }

    public function withDraw($amount){
        $this->amount -= $amount;
    }

    public function getBalance(){
        echo "Balance in Saving Account is ".$this->amount."<br>";
    }
}

$saving = new SavingAccount(1000, "John");
$saving->deposit(500); // Deposit: 500
$saving->getBalance();  // Balance in Saving Account is 1500
$saving->withDraw(200); // Withdraw: 200
$saving->getBalance();  // Balance in Saving Account is 1300

?>
            
        

In the above code, the SavingAccount class implements the BankAccount interface. This means the SavingAccount class is required to implement the deposit, withDraw, and getBalance methods defined in the BankAccount interface.

This example illustrates how interfaces in PHP can be used to enforce certain behaviors in classes. By implementing the BankAccount interface, the SavingAccount class is guaranteed to have the methods necessary for managing a bank account, thus ensuring consistency across different types of accounts.

FAQs on Implementing Interfaces in PHP

---