Displaying Arrays in PHP using Object Oriented Programming - php

Question

I'm experimenting with PHP and object oriented programming in PHP. When I try to run the following displayArray function, it does not display the line at all. Does anyone know what I'm doing wrong?
<?php
class Student
{
var $name;
var $arr;
function Student()
{
$this->name = "bob";
$this->addnametostring("Hello there ");
$this->arr = array();
for($i=0; $i<30; $i++) {
$arr[$i] = rand(0,100);
}
}
function addnametostring($s)
{
$s.= " " . $this->name;
echo "$s <br>";
}
function displayArray($amt)
{
foreach($this->arr as $key) {
//why is this not working
echo "<br>hello: ".$key;
}
}
}
$student = new Student;
echo "<br>";
$student->displayArray(20);
?>

Answer 1

Change this
for($i=0; $i<30; $i++){
$arr[$i] = rand(0,100);
}
to
for($i=0; $i<30; $i++){
$this->arr[$i] = rand(0,100);
}
EDIT: Did not notice you are missing your constructor, so your entire class should look like this
class Student(){
var $name;
var $arr;
public function __construct() {
$this->name = "bob";
$this->addnametostring("Hello there ");
$this->arr = array();
for($i=0; $i<30; $i++){
$this->arr[$i] = rand(0,100);
}
}
function addnametostring($s){
$s.= " " . $this->name;
echo "$s <br>";
}
function displayArray($amt){
foreach($this->arr as $key){
//why is this not working
echo "<br>hello: ".$key;
}
}
}

Answer 2

in php constructer is as follow
function __construct(){
//some code
}
so you are not calling student function.

Answer 3

You can use a constructor to easily assign the array when you first call the class.
<?php
class Student
{
public $name;
public $arr;
function __construct()
{
$this->name = "bob";
$this->addnametostring("Hello there ");
$this->arr = array();
for($i=0; $i<30; $i++) {
$this -> arr[$i] = rand(0,100);
}
}
function addnametostring($s)
{
$s.= " " . $this->name;
echo "$s <br>";
}
function displayArray()
{
foreach($this->arr as $key) {
//why is this not working
echo "<br>hello: ".$key;
}
}
}
Then,
$student = new Student;
echo "<br>";
$student-> displayArray();
I'm not sure why you had $amt variable.
Thanks.