'': is an empty string
0: is not an empty string
false: is an empty string
true: is not an empty string
NULL: is an empty string
-1: is not an empty string
array (
): is not an empty string
1: is not an empty string
'0': is not an empty string
'1': is not an empty string
'': is an empty string
0: is an empty string
false: is an empty string
true: is not an empty string
NULL: is an empty string
-1: is not an empty string
array (
): is not an empty string
1: is not an empty string
'0': is not an empty string
'1': is not an empty string