php ternary operator formatting

Question

This works:

\"/>

This does n

Answer 1

PHP's operator precedence rules make it evaluate your second example as follows:

echo(
  ('')
);

That doesn't make a lot of sense in several ways. And since the result of isset() is essentially disregarded, this always ends up just trying to print $_POST['foo']. And that results in a notice when it's not set, of course.

Add parentheses around the actual ternary expression. I.e.

(isset($_POST['foo']) ? $_POST['foo'] : '')