Unary operator overloading in c++ becomes very handy when you deal with user defined data types and you want to apply arithmetic meaning to the objects like you want to perform minus operation on object, in these kind of situations it is very much important to overload unary operators.
If we don’t use unary operators we can use the traditional function calling way but unary operator overloading makes your programming logic look more intuitive.
Introduction To Operator Overloading In C++ :