Question

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;

Answer 1

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.