what does comma in echo statement signify?

Question

I am trying to echo a string from a Recursive function:
echo \"

\", $node, recurse($arr), \"

\";
and
echo \"

\" .

Answer 1

echo is a language construct and can accept multiple arguments separated by a comma. The effect is identical to a concatenated string.

The output shouldn't be different - I can't think of an instance where it could be.

Edit: Ah, but it is. That is because your function echo()es stuff. In the first instance,