PHP How to access variable from other variable inside class?

Question

Here is my class:

<?php
class myClass {
    private $a = 1;
    private $b = array(
        'a' => $this->a
    );

    public function getB() {
        return $this->b;
    }
}

$myclass = new myClass();
var_dump($myclass->getB());

I want to access variable $a in variable $b. But this shows this error:

( ! ) Parse error: syntax error, unexpected '$this' (T_VARIABLE) in C:\xampp\htdocs\test1.php on line 5

$this is not defined when class variables are declared. After __construct is called you can access $this — algorhythm
– algorhythm, Commented Jun 25, 2014 at 13:23
It's true that can not use $this if class members are not declared. __construct seems the best solution. But I'm trying to use const instead of normal variable. — Nguyễn Trọng Bằng
– Nguyễn Trọng Bằng, Commented Jun 25, 2014 at 14:01

Gladen · Accepted Answer · 2014-06-25 13:20:58Z

2

You are not allowed to assign a variable property this way. The best way is to probably assign the variable to the array in the constructor instead. So, like this:

<?php
class myClass {
    private $a = 1;
    private $b = array();

    public function __construct() {
        $this->b['a'] = $this->a;
    }

    public function getB() {
        return $this->b;
    }
}

$myclass = new myClass();
var_dump($myclass->getB());

edited Jun 25, 2014 at 13:20

answered Jun 25, 2014 at 13:04

Gladen

8022 gold badges9 silver badges17 bronze badges

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

2 Comments

Gladen Over a year ago

You can't. You're only allowed to assign a constant value directly after declaration. But a variable value (what you are trying) is not allowed. That is were the constructor is designed for. More about it can be found here: php.net/manual/en/language.oop5.properties.php

Nguyễn Trọng Bằng Over a year ago

You're right. The best solution is using constructor.

onuri · Accepted Answer · 2014-06-25 13:02:52Z

1

You can access variables by constructor.

Here is some code:

class myClass {
    private $a;
    private $b;

    public function __construct(){
        $this->a = 1;
        $this->b = array('a'=>$this->a);
    }

    public function getB() {
        return $this->b;
    }
}

$myclass = new myClass();
var_dump($myclass->getB());

answered Jun 25, 2014 at 13:02

onuri

1701 silver badge6 bronze badges

1 Comment

onuri Over a year ago

You can find some info from php manual. Take a look : php.net/manual/en/language.oop5.properties.php

Collectives™ on Stack Overflow

PHP How to access variable from other variable inside class?

2 Answers 2

2 Comments

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related