In C++ we can make primitives unsigned. But they are always positive. Is there also a way to make unsigned negative variables? I know the word unsigned means "without sign", so also not a minus (-) sign. But I think C++ must provide it.
No. unsigned can only contain nonnegative numbers.
If you need a type that only represent negative numbers, you need to write a class yourself, or just interpret the value as negative in your program.
(But why do you need such a type?)