PHP - Modify array value by reference inside object

Question

How can I pass a value of an array by reference to modify its value inside an object? I've tried it with the & operator at public function f(&$z) {.

<?php
    class C {
        private $a;

        public function f($z) {
            foreach ($z as $i => $v) {
                $v = 8888;
            }
        }
    }

    $p = 4;
    $obj = new C();
    $obj->f(array('key'=>$p));
    echo $p;
?>

I would like to set the 8888 value to the $p variable.

The fiddle: http://codepad.org/RvKU4hY1

@vp_arth When I do this, I just get an error: Fatal error: Cannot pass parameter 1 by reference — felipe.zkn
– felipe.zkn, Commented Apr 11, 2014 at 16:32

gog · Accepted Answer · 2014-04-11 16:31:16Z

2

You have to use references when you 1) create the array, 2) iterate over it:

<?php
  class C {
    private $a;

    public function f($z) { 
        foreach ($z as $i => &$v) {
            $v = 8888;
        }
    }
  }
    $p = 4;
    $obj = new C();
    $obj->f(array('key'=>&$p));
    echo $p;
?>

answered Apr 11, 2014 at 16:31

gog

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1 Comment

gog Over a year ago

@felipe.zkn: please see the edit - you actually only need two of them.

tbddeveloper · Accepted Answer · 2014-04-11 16:32:52Z

2

Only slightly different to georg, you can do it this way;

<?php
class C {
    private $a;

    public function f($z) {
        foreach ($z as $i => $v) {
            $z[$i] = 8888;
        }
    }
}
$p = 4;
$obj = new C();
$result = array('key'=> &$p);
$obj->f($result);

echo $p;
?>

answered Apr 11, 2014 at 16:32

tbddeveloper

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Comments

vp_arth · Accepted Answer · 2014-04-11 16:39:12Z

2

Here the code with explanation:

<?php
    class C {
        private $a;

        public function f(&$z) { // we receive a pointer
            foreach ($z as $i => $v) {
                //  here you overwrite $v, even if it a pointer in foreach
                // It has mean when you want to do unset($v); here
                // $v = 8888;
                $z[$i] = 8888;
            }
        }
    }

    $p = 4;
    $obj = new C();
    $param = array('key'=>$p);
    $obj->f($param);
    echo $p;

edited Apr 11, 2014 at 16:39

answered Apr 11, 2014 at 16:33

vp_arth

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