I would like to access class variables with for loop, here is my simple class

class test{
    public $var1 = 1;
    public $var2 = 2;
    public $var3 = 3;
    public $var4 = 4;
}


$class = new test();

this is how i try to access variables with a loop

for($i = 1; $i <= 4; $i++){
    echo $class->var.$i;
}

and i get error which says Notice: Undefined property: test::$var in C:\xampp\htdocs\test\index.php on line 12

Well it's not really a big error and i actualy get the value echoed but i still don't understand why do i get this error?

also if i do it this way everything works fine:

echo $class->var1;

• php
• oop

You're not actually getting the value echoed, you're getting $i echoed.

echo $class->var.$i; is being interpreted as echo ($class->var).($i);. Since var isn't a variable (hence the error), it becomes echo ''.$i;, so you get the value of $i. It just so happens that var1 has the value 1. (Change $var1 to something else, and you'll see what I mean)

To fix the issue, you can do this:

for($i = 1; $i <= 4; $i++){
    $class->{'var'.$i}
}

The stuff inside the {} is calculated first, so the correct property is read.

for($i = 1; $i <= 4; $i++){
    $var = 'var' . $i;
    echo $class->$var;
}

Or, as mentioned in the comments, this will work in newer versions of PHP

for($i = 1; $i <= 4; $i++){
    $class->{'var' . $i}
}

The code isn't doing what you think. It's only echoing 1-4 because of your $i in the for loop. If you were to change the vars in the class, your output will still be 1-4.

The undefined property notices is the clue: it is trying to access the property var.

If you want to store data that is repetitive and/or associated, especially like in your example, it is usually more suitable to store as an array:

class test{
    public $vars;

    public function __construct()
    {
        $this->vars = array(1, 2, 3, 4);
    }
}

$obj = new test();

foreach($obj->vars as $var)
{
    echo $var;
}

The dot (.) operator is getting used by the echo rather than the member call to $class.

One of many solutions:

for($i = 1; $i <= 4; $i++){
     echo $class->{'var'.$i};
}

live example here

This already works fine on very recent PHP versions, but try this:

for($i = 1; $i <= 4; $i++){
    $v = 'var'.$i;
    echo $class->$v;
}