What is a constructor in PHP?

A constructor in PHP is defined as a special method that is automatically called when an object is instantiated from a class. This method allows for the initialization of object properties and the setting up of any necessary resources or initial state that the object requires upon creation. This means that when you create a new instance of a class, the constructor is executed right away, allowing you to perform setup tasks such as assigning default values to properties or performing any required calculations.

The significance of the constructor lies in ensuring that the object starts its life in a known and valid state. It can also accept parameters, allowing for dynamic initialization based on the values passed during object creation.

The other options refer to different aspects of object lifecycle management in PHP. A method that is called when an object is destroyed relates to destructors, which are used for cleanup tasks when an object is no longer needed. Cloning an object involves a different mechanism entirely, utilizing the __clone magic method, not the constructor. Therefore, the function of a constructor is specifically tied to the creation of objects and the initial setup of their state.