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(
  ('<input type="text" name="foo" value="'.isset($_POST['foo']))
    ? $_POST['foo']
    : (''.'"/>')
);

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'] : '')

Answer 2

Put the expression in the parenthesis:

echo('<input type="text" name="foo" value="'. (isset($_POST['foo']) ? $_POST['foo'] : '') .'"/>');

Answer 3

IMHO, parenthesis (as suggested by zerkms) makes code unreadable.

Instead, think something like this:

$value = isset($_POST['foo']) ? $_POST['foo'] : '';
echo '<input type="text" name="foo" value="'. $value .'"/>';