PHP: Right way to declare variable before use in loop

Question

I have a variable that is built in loop. Something like:

$str = "";
for($i = 0; $i < 10; $i++) $str .= "something";

If $str = "" is ommitted, I get undefined variable notice, but I thought php auto-declare a variable the first time it sees undeclared one?

How do I do this right?

Answer 1

You get the undefined variable because you're concatenating the value of itself with another value.

The equivalent of

$str = $str . "something";

So, it can't say what's the initial value is. It's the equivalent of this:

$str = [undefined value] . "something";

What's the result of a concatenation of [undefined value] and "something"? The interpreter can't say...

So, you have to put "" in the variable first to initiate the variable's value, as you did.

HTH