Question

I’m going through some Zend PHP certification questions and am stuck on this one:

What is the output of the following:

<?php

class Magic{

    public $a = "A";
    protected $b = array("a" => "A", "b" => "B", "c" => "C");
    protected $c = array(1,2,3);

    public function __get($v){
        echo "$v,";
        return $this->b[$v];
    }

    public function __set($var, $val){
        echo "$var: $val,";
        $this->$var = $val;
    }

}

$m = new Magic();
echo $m->a.",".$m->b.",".$m->c.",";
$m->c = "CC";
echo $m->a.",".$m->b.",".$m->c;

Answer: b,c,A,B,C,c: CC,b,c,A,B,C

I know that __get() and __set are called when trying to access/set inaccessible properties but can someone tell me what happens to the $m->a? I.e why does it disappear?

Thanks in advance

Answer 1

echo $m->a.",".$m->b.",".$m->c.",";

Note that the string is being concatenated, but that __get outputs the name of the key. The lower case letters are key names, the upper case letters are the values.

b,c,A,B,C,c: CC,b,c,A,B,C

a is accessed normally, not through __get, b and c are accessed through __get and the keys are echo‘d first, their value is then returned, concatenated into the string and output after the output of “b,c,”.

So what this shows is that the __get method is triggered for b and c but not for a, then the values “A”, “B” and “C” are output, then the value “CC” is set, then b and c are accessed through __get again, then “A”, “B” and “C” are output again.