How i store Objects in an Array with a set function in php?

Question

I searched many solutions here on Stackflow but i dont get it fixed. Its simple i have a class Library and i want to store Books object there and display them. My code is simple but i dont get it. I am getting this ERROR: Undefined variable: books

        class Library{

             var $books = array();

            function addBook($bok){
                $books[] = $bok;
            }

            function displayBooks(){
                foreach($books as $b){
                    $b->display();
                }
            }
        }

        class Book{
            var $title;
            function __construct($name){
                $this->title = $name;
            }

            function display(){
                echo $this->title;
            }
        }


        $lib = new Library();
        $lib->addBook(new Book("Test Title"));
        $lib->displayBooks();

from inside the class, the variable should be referred to as $this->books and not $books — Calimero
– Calimero, Commented Sep 19, 2017 at 13:10
Also, please note, that var not recommended since release of PHP 5.0 (that was in 2006 or so) ... you might need to get a newer tutorial/book. — tereško
– tereško, Commented Sep 19, 2017 at 13:17
what you mean? i cant dont write var ist part of the syntax i tested it? what i schould use instead? — Darius Mann
– Darius Mann, Commented Sep 19, 2017 at 13:18

Enrico Agrusti · Accepted Answer · 2017-09-19 13:21:41Z

2

$books is your instance variable of Library, but to access it you should write $this->books, not $books. (As Calimero commented under the question)

Also, it's a good practice to always make explicit use of the visibility (public, private, protected).

Example:

class Library {
  private $books = [];
  public function addBook($book){
    $this->books[] = $book;
  }

  public function displayBooks(){
    foreach($this->books as $b){
      $b->display();
    }
  }
}

edited Sep 19, 2017 at 13:21

answered Sep 19, 2017 at 13:14

Enrico Agrusti

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Comments

tlorens · Accepted Answer · 2017-09-19 13:12:38Z

0

Need to reference your class array with $this. Example below.

function addBook($book) {
    $this->books[] = $book;
}

function displayBooks() {
    foreach($this->books as $book){
        $book->display();
    }
}

answered Sep 19, 2017 at 13:12

tlorens

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