php - Why check both isset() and !empty()

Question

Is there a difference between isset and !empty. If I do this double boolean check, is it correct this way or redundant? and is there a shorter way to do the same thing?

isset($vars[1]) AND !empty($vars[1])

Answer 1

This is completely redundant. empty is more or less shorthand for !isset($foo) || !$foo, and !empty is analogous to isset($foo) && $foo. I.e. empty does the reverse thing of isset plus an additional check for the truthiness of a value.

Or in other words, empty is the same as !$foo, but doesn't throw warnings if the variable doesn't exist. That's the main point of this function: do a boolean comparison without worrying about the variable being set.

The manual puts it like this:

empty() is the opposite of (boolean) var, except that no warning is generated when the variable is not set.

You can simply use !empty($vars[1]) here.