Class methods are functions defined inside a class.
Like functions, methods can have arguments and perform some actions, optionally returning a value.
Methods inside class can use the properties of the object that invoked them.
Calling the same method in two different objects might have two different results.
<?php class Book { public $isbn; public $title; public $author; public $available; public function getPrintableTitle(): string { $result = $this->title . '\n' . $this->author; if (!$this->available) { $result .= 'Not available'; } //from w ww. jav a 2 s . c o m return $result; } public function getCopy(): bool { if ($this->available < 1) { return false; } else { $this->available--; return true; } } } $book = new Book(); $book->title = "2018"; $book->author = "C"; $book->isbn = 0003; $book->available = 12; if ($book->getCopy()) { echo 'Here, your copy.'; } else { echo 'I am afraid that book is not available.'; } ?>