Can I use an std::map with both keys and values being enum classes in C++11?

Question

I need a way of mapping C++11 `enum classes` to other `enum classes`. Let's say I have these C++11 style enums: ``` #include #include class Foobar { public: enum class Lecture { COMP_SCI, PHYSICS, CHEMISTRY, BIOLOGY, PSYCHOLOGY, MODERN_ART, PHILOSOPHY, SOCIOLOGY }; enum class Day { MONDAY, TUESDAY, WEDNESDAY, THURSDAY, FRIDAY, SATURDAY, SUNDAY }; }; void test_enum_class_to_enum_class_std_map() { std::map lectureToDayMap; lectureToDayMap.insert(Foobar::Lecture::COMP_SCI, Foobar::Day::MONDAY); } int main(int argc, char** argv) { test_enum_class_to_enum_class_std_map(); return 0; } ``` Is there a way of mapping from one enum class to another? I want something like `std::map lectureToDayMap;` If this isn't possible, am I able to convert from an `int` to an `enum class` and vice versa so I can just use a `std::map` map and convert to `int` to insert, and back to an `enum class` to retrieve a value? Here…

Accepted Answer

According to http://en.cppreference.com/w/cpp/container/map std::map is a sorted associative container that contains key-value pairs with unique keys. Therefore you must insert a pair.

Replace

```
 lectureToDayMap.insert(Foobar::Lecture::COMP_SCI, Foobar::Day::MONDAY);
```

by

```
mymap.insert(std::make_pair(Foobar::Lecture::COMP_SCI, Foobar::Day::MONDAY));
```

or better

```
lectureToDayMap[Foobar::Lecture::COMP_SCI] = Foobar::Day::MONDAY;
```

Can I use an std::map with both keys and values being enum classes in C++11?

Solution

Problem