attempting to initialize php variables in constructor, getting error

Question

I'm trying to initialize a class attribute within a php constructor method, but am getting the error:

Notice: Undefined variable: _board in C:\wamp\scaleUp\back\objects.php on line 9

code:

<?php
class Board {
public function __construct(){
    for ($x = 9; $x >= 0; $x--) {
        for ($y = 0; $y<10; $y++){
            $row = array();
            $row[$y] = $y;
        }
        $this->$_board = array(); 
            $this->$_board[$x] = $row;
    }
    echo "here";
    echo $this->$board[$x];
}       

 }

 $board =  new Board();

 ?>

This is a typo question. Your code is unnecessarily complex for future Stack Overflow readers, so here is a later asked dupe that is easier on the eyes: Failing to assign value for public property in constructor — mickmackusa
– mickmackusa ♦, Commented Feb 23, 2024 at 7:20

ThiefMaster · Accepted Answer · 2012-05-26 09:46:24Z

2

The syntax to access an object field is $obj->field, not $obj->$field (unless you want to access the field name that is stored in $field).

answered May 26, 2012 at 9:46

ThiefMaster

320k85 gold badges608 silver badges648 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Tabrez Ahmed · Accepted Answer · 2012-05-26 09:59:13Z

1

Here, I have debugged the code for you.

<?php
class Board {
public $_board;
public function __construct(){
    for ($x = 9; $x >= 0; $x--) {
        for ($y = 0; $y<10; $y++){
            $row = array();
            $row[$y] = $y;
        }
        $this->_board = array(); 
            $this->_board[$x] = $row;
    }
    echo "here";
    echo $this->_board[$x+1];/*OR*/print_r($this->_board[$x+1]);
    //$x had to be incremented here.
}       

 }

 $board =  new Board();

 ?>

As others mentioned, you have to follow the syntax: $obj->property, not $obj->$property.

answered May 26, 2012 at 9:59

Tabrez Ahmed

3,0007 gold badges35 silver badges51 bronze badges

Comments

Spudley · Accepted Answer · 2012-05-26 19:55:29Z

1

remove the $ from _board -

$this->_board = array();

edited May 26, 2012 at 19:55

Spudley

169k39 gold badges240 silver badges309 bronze badges

answered May 26, 2012 at 9:47

Mukesh Soni

6,6683 gold badges34 silver badges38 bronze badges

Comments

Ayush · Accepted Answer · 2012-05-26 09:46:37Z

0

It should be

$this->board

You don't need the second $ sign.

Also, in your constructor, in the inner loop, you are re-initializing $row as an array in every iteration. Is that intended?

answered May 26, 2012 at 9:46

Ayush

42.5k52 gold badges170 silver badges243 bronze badges

Comments

Muhannad A.Alhariri · Accepted Answer · 2012-05-26 09:49:43Z

0

You have to define your variable as a member variable suck as

class object {
 $_board ;
...
...
...
}

and when you want to use it you have to use the following syntax

$this->_board = .....;

I hope this helps you

answered May 26, 2012 at 9:49

Muhannad A.Alhariri

3,9524 gold badges33 silver badges48 bronze badges

Collectives™ on Stack Overflow

attempting to initialize php variables in constructor, getting error

5 Answers 5

Comments

Comments

Comments

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

5 Answers 5

Comments

Comments

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related