If Iterator::valid() returns false, the foreach() loop will be terminated.
(PHP 5, PHP 7, PHP 8)
Iterator::valid — Checks if current position is valid
This method is called after Iterator::rewind() and Iterator::next() to check if the current position is valid.
У цієї функції немає параметрів.
If Iterator::valid() returns false, the foreach() loop will be terminated.
If your class implements also ArrayAccess interface, you could use as valid() body
function valid(){
return $this->offsetExists($this->position);
}