Explain ArrayAccess interface in php

In PHP, the ArrayAccess interface provides a way to interact with objects as if they were arrays. This means you can use array syntax to access, set, unset, and check the existence of elements within an object, just like you would with a regular array.

The ArrayAccess interface consists of four methods that need to be implemented by the class that implements this interface:

1. offsetExists($offset): This method is called to check whether an offset exists in the object. It is invoked using the isset function.

2. offsetGet($offset): This method is called to retrieve the value associated with a given offset. It is invoked using the array syntax $object[$offset].

3. offsetSet($offset, $value): This method is called to set the value associated with a given offset. It is invoked using the array syntax $object[$offset] = $value.

4. offsetUnset($offset): This method is called to unset the value associated with a given offset. It is invoked using the unset function.

Here's a simple example to illustrate the usage of ArrayAccess:

php
class SampleArrayAccess implements ArrayAccess {
    private $data = [];

    public function offsetExists($offset) {
        return isset($this->data[$offset]);
    }

    public function offsetGet($offset) {
        return $this->data[$offset] ?? null;
    }

    public function offsetSet($offset, $value) {
        $this->data[$offset] = $value;
    }

    public function offsetUnset($offset) {
        unset($this->data[$offset]);
    }
}

// Usage
$obj = new SampleArrayAccess();

// Set value
$obj['key'] = 'value';

// Get value
echo $obj['key']; // Outputs: value

// Check if offset exists
echo isset($obj['key']) ? 'Exists' : 'Does not exist'; // Outputs: Exists

// Unset value
unset($obj['key']);
echo isset($obj['key']) ? 'Exists' : 'Does not exist'; // Outputs: Does not exist

In this example, the SampleArrayAccess class implements the ArrayAccess interface, allowing instances of the class to be accessed using array syntax.