How to easily map c++ enums to strings

If you want the enum names themselves as strings, see this post. Otherwise, a std::map<MyEnum, char const*> will work nicely. (No point in copying your string literals to std::strings in the map)

For extra syntactic sugar, here's how to write a map_init class. The goal is to allow

std::map<MyEnum, const char*> MyMap;
map_init(MyMap)
    (eValue1, "A")
    (eValue2, "B")
    (eValue3, "C")
;

The function template <typename T> map_init(T&) returns a map_init_helper<T>. map_init_helper<T> stores a T&, and defines the trivial map_init_helper& operator()(typename T::key_type const&, typename T::value_type const&). (Returning *this from operator() allows the chaining of operator(), like operator<< on std::ostreams)

template<typename T> struct map_init_helper
{
    T& data;
    map_init_helper(T& d) : data(d) {}
    map_init_helper& operator() (typename T::key_type const& key, typename T::mapped_type const& value)
    {
        data[key] = value;
        return *this;
    }
};

template<typename T> map_init_helper<T> map_init(T& item)
{
    return map_init_helper<T>(item);
}

Since the function and helper class are templated, you can use them for any map, or map-like structure. I.e. it can also add entries to std::unordered_map

If you don't like writing these helpers, boost::assign offers the same functionality out of the box.

MSalters solution is a good one but basically re-implements boost::assign::map_list_of. If you have boost, you can use it directly:

#include <boost/assign/list_of.hpp>
#include <boost/unordered_map.hpp>
#include <iostream>

using boost::assign::map_list_of;

enum eee { AA,BB,CC };

const boost::unordered_map<eee,const char*> eeeToString = map_list_of
    (AA, "AA")
    (BB, "BB")
    (CC, "CC");

int main()
{
    std::cout << " enum AA = " << eeeToString.at(AA) << std::endl;
    return 0;
}

Auto-generate one form from another.

Source:

enum {
  VALUE1, /* value 1 */
  VALUE2, /* value 2 */
};

Generated:

const char* enum2str[] = {
  "value 1", /* VALUE1 */
  "value 2", /* VALUE2 */
};

If enum values are large then a generated form could use unordered_map<> or templates as suggested by Constantin.

Source:

enum State{
  state0 = 0, /* state 0 */
  state1 = 1, /* state 1 */
  state2 = 2, /* state 2 */
  state3 = 4, /* state 3 */

  state16 = 0x10000, /* state 16 */
};

Generated:

template <State n> struct enum2str { static const char * const value; };
template <State n> const char * const enum2str<n>::value = "error";

template <> struct enum2str<state0> { static const char * const value; };
const char * const enum2str<state0>::value = "state 0";

Example:

#include <iostream>

int main()
{
  std::cout << enum2str<state16>::value << std::endl;
  return 0;
}

How to easily map c++ enums to strings

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