Need help with the code

i need help guys as my php sucks. can someone make it "copy by reference"? and Loop them and also Debug? i have no idea what is copy by reference from copy by value.... prof told me its only the job to change or check 10 lines. but i have no idea what he is talking about.

file1-person.php
<?php

// this class will represent both a Person and a Child in the society
class Person {
var $id;
var $age;
var $children;
function Person( $id, $age) {
$this->id = &$id;
$this->age = &$age;
// all children if any are added will be places into this array
$this->children = array();
}
function addChild( $child) {
array_push( $this->children, $child);
}

}

?>



file 2-init.php
<?php

require_once( 'Person.php');

/**
* Rules of society:
* 1. Whenever a person reaches the age of 100, he dies
* 2. At initiation, a person may be given a number of children,
* each of age from 0 to 10
* 3. A Child is a full-fledged person and should be treated as such
* 4. Society is becoming extinct, since no new children are born into it
*/

// this array contains the entire society
$society = array();
$id = 0; // this will be used to give unique id to everyone in society
// create 100 people of age
for ( $i = 0; $i < 100; $i++) {
// create a new person with a random age between 20 and 50
// mt_rand is a PHP random number generator function
$person = new Person( $i, mt_rand( 20, 50));
$id++; // next person will have another id
if ( mt_rand( 0, 1) === 0) { // 50/50 change of adding children to this person
$count = mt_rand( 1, 5); // add between 1 and 5 chidren to this person
for ( $y = 0; $y < $count; $y++) {
$person->addChild( new Person( $id, mt_rand( 0, 20)));
$id++; // next child or person will have another id
}

}
array_push( $society, $person);
}

?>

 

Use the vbulletin PHP tags ... like this

<?php

// this class will represent both a Person and a Child in the society
class Person {
    var $id;
    var $age;
    var $children;
    function Person( $id, $age) {
        $this->id = &$id;
        $this->age = &$age;
        // all children if any are added will be places into this array
        $this->children = array();
    }
    function addChild( $child) {
        array_push( $this->children, $child);
    }
   
}

?>

PHP:

file 2-init.php

<?php

require_once( 'Person.php');

/**
*    Rules of society:
*        1. Whenever a person reaches the age of 100, he dies
*        2. At initiation, a person may be given a number of children,
*                each of age from 0 to 10
*        3. A Child is a full-fledged person and should be treated as such
*        4. Society is becoming extinct, since no new children are born into it
*/

// this array contains the entire society
$society = array();
$id = 0;        // this will be used to give unique id to everyone in society
// create 100 people of age
for ( $i = 0; $i < 100; $i++) {
    // create a new person with a random age between 20 and 50
    // mt_rand is a PHP random number generator function
    $person = new Person( $i, mt_rand( 20, 50));
    $id++;        // next person will have another id
    if ( mt_rand( 0, 1) === 0) { // 50/50 change of adding children to this person
        $count = mt_rand( 1, 5);        // add between 1 and 5 chidren to this person
        for ( $y = 0; $y < $count; $y++) {
            $person->addChild( new Person( $id, mt_rand( 0, 20)));
            $id++;    // next child or person will have another id
        }
       
    }
    array_push( $society, $person);
}

?>

PHP:

 

thank you very much
left reps for you.
I appreciate it