如何在PHP类中创建关联数组

Question

This is my language class. Is it possible to create array as below? I tried but my compiler is throwing error. If its outside class i can create that array. But why cant i do the same from within class

Does not work

class Language{
    private $LANG = array();

    /*
    ERROR CODE
    1   DATABASE
    2   EMPTY USERNAME AND PASSWORD
    */

    //1   DATABASE
    $LANG[1]["TITLE"] = "DATABASE CONNECTION ERROR";
    $LANG[1]["MESSAGE"] = "PLEASE CONTACT YOUR ADMISTRATOR";

    //2   EMPTY USERNAME AND PASSWORD
    $LANG[2]["TITLE"] = "LOGIN ERROR";
    $LANG[2]["MESSAGE"] = "INVALID USERNAME OR PASSWORD";

    //3   EMPTY QUERY ERROR
    $LANG[3]["TITLE"] = "ERROR";
    $LANG[3]["MESSAGE"] = "UNABLE TO COMMUNICATE WITH SERVER";
}

It works

    private $LANG = array();

    /*
    ERROR CODE
    1   DATABASE
    2   EMPTY USERNAME AND PASSWORD
    */

    //1   DATABASE
    $LANG[1]["TITLE"] = "DATABASE CONNECTION ERROR";
    $LANG[1]["MESSAGE"] = "PLEASE CONTACT YOUR ADMISTRATOR";

    //2   EMPTY USERNAME AND PASSWORD
    $LANG[2]["TITLE"] = "LOGIN ERROR";
    $LANG[2]["MESSAGE"] = "INVALID USERNAME OR PASSWORD";

    //3   EMPTY QUERY ERROR
    $LANG[3]["TITLE"] = "ERROR";
    $LANG[3]["MESSAGE"] = "UNABLE TO COMMUNICATE WITH SERVER";

Answer 1

First. You can't have a code in the class definition outside of method. You need to wrap it in a method.

Second. If you want to operate on class instance's property you have to use the this-> keyword to indicate that.

So your code can look like:

class Language
{
    private $LANG = array();

    function __construct()
    {
        /*
        ERROR CODE
        1   DATABASE
        2   EMPTY USERNAME AND PASSWORD
        */

        //1   DATABASE
        $this->LANG[1]["TITLE"] = "DATABASE CONNECTION ERROR";
        $this->LANG[1]["MESSAGE"] = "PLEASE CONTACT YOUR ADMISTRATOR";

        //2   EMPTY USERNAME AND PASSWORD
        $this->LANG[2]["TITLE"] = "LOGIN ERROR";
        $this->LANG[2]["MESSAGE"] = "INVALID USERNAME OR PASSWORD";

        //3   EMPTY QUERY ERROR
        $this->LANG[3]["TITLE"] = "ERROR";
        $this->LANG[3]["MESSAGE"] = "UNABLE TO COMMUNICATE WITH SERVER";
    }

    function getData()
    {
        return $this->LANG;
    }
}

$lang = new Language();
var_dump($lang->getData());

You can read more about it in the documentation: https://www.php.net/manual/en/language.types.object.php

EDIT: Demo here https://3v4l.org/qVtD9