Determine whether a variable is considered to be empty. A variable is considered empty if it does not exist or if its value equals false. empty does not generate a warning if the variable does not exist.
Variable to be checked
No warning is generated if the variable does not exist. That means empty is essentially the concise equivalent to !isset($var) || $var == false.
Returns true if var does not exist or has a value that is empty or equal to zero, aka falsey, see conversion to boolean. Otherwise returns false.
Because this is a language construct and not a function, it cannot be called using variable functions, or named arguments.
When using empty on inaccessible object properties, the __isset() overloading method will be called, if declared.