std::map default value for enums

Question

Let's say we have:

enum X {
  X1,
  X2,
  X3
};

int func() {
  std::map<int, X> abc;
  ...
}

Assume 0 is the key that is not in the container.

I know abc[0] needs to value-initialize the X object.

Here are the questions:

(1) Will the initialization always be zero-initialization for enumerations? namely abc[0] is always initialized as the enumerator corresponding to 0?

(2) What if we have

enum X {
  X1 = 1,
...

What will abc[0] be?

Answer 1

Will the initialization always be zero-initialization for enumerations? namely abc[0] is always initialized as the enumerator corresponding to 0?

Yes.

What if we have

enum X {
   X1 = 1,
   ...

What will abc[0] be?

It will be 0.

Working program (also can be seen at http://ideone.com/RVOfT6):

#include <iostream>
#include <map>

enum X {
  X1,
  X2,
  X3
};

int main()
{
   X x = {};
   std::map<int, X> abc;
   std::cout << x << std::endl;
   std::cout << abc[0] << std::endl;
}

Output:

0
0