PHP/Data Type/empty

bool empty ( mixed var ) returns true if its parameter has a false value

 
$var1 = "0";
    $var2 = "1";
    $var3 = "";
    if (empty($var1)) print "Var1 empty\n";
    if (empty($var2)) print "Var2 empty\n";
    if (empty($var3)) print "Var3 empty\n";
    if (empty($var4)) print "Var4 empty\n";