I am trying to add unique pointer to map.
auto monkey= std::unique_ptr<Animal> (new Animal(1,"Tom"));
std::map<int, std::unique_ptr<const Animal>> animals; //Map of animals
animals.insert(pair<int, unique_ptr<Animal>>(1,monkey)); // Error here
Error:error: no matching function for call to 'std::pair<int, std::unique_ptr<Animal> >::pair(int&, std::unique_ptr<Animal>&)'
what would be the way to add it ??
std::unique_ptr is not copiable, but movable, you have to std::move it.
You might do:
animals.emplace(1, std::move(monkey));
I would suggest you using the following when trying to insert std::unique_ptr into the std::map:
animals.insert(std::make_pair(1, std::unique_ptr<Animal>(new Animal(1,"Tom"))));
or
animals.insert(std::make_pair(1, std::make_unique<Animal>(1,"Tom")));
First, prefer using std::make_pair over std::pair constructor because with std::pair you need to specify the types of both elements, whereas std::make_pair will deduce the types of the elements that are passed to it.
Second, as the other answer says, std::unique_ptr can't be copied because it is unique. It can only be moved by std::move. In this case, since you are passing an r-value reference to the std::make_pair function it is being moved.
myMap.insert(std::make_pair(0, std::unique_ptr<Class1>(new Class1())));on your exampleanimals.insert(pair<int, unique_ptr<Animal>>(1,std::move(monkey)));unique_ptr can be only moved, not copied.