What is the use of this( . ' ' ) in above program after echo $i

Question

<?php
for ($i=0; $i<10; $i++) {
if ($i%2==0) {
continue;
}
echo $i . ' ';
}
?>

Answer 1

It is just a space which separate printed numbers.

Answer 2

You can use from . to sum strings or variables with themselves.
So when you sum anything with ' ' , the result is one separate after or before your output text.