C++: Get size of enum


We used the following application in C++ to test the size of an enum:

#include <iostream>
using namespace std;

enum SINGLE {
        S_ZERO = 0x0,
        S_FULL = 0xFFFFFFFF
};

enum DOUBLE {
        D_ZERO = 0x0,
        D_FULL = 0xFFFFFFFFFFFFFFFF
};

int main() {
        cout << "Single Zero: Size '" << sizeof(S_ZERO) << "' Value '" << S_ZERO << "'" << endl;
        cout << "Double Zero: Size '" << sizeof(D_ZERO) << "' Value '" << D_ZERO << "'" << endl;

        cout << "Single Full: Size '" << sizeof(S_FULL) << "' Value '" << S_FULL << "'" << endl;
        cout << "Double Full: Size '" << sizeof(D_FULL) << "' Value '" << D_FULL << "'" << endl;
        return 0;
}

The output we got is the following:

Single Zero: Size '4' Value '0'
Double Zero: Size '8' Value '0'
Single Full: Size '4' Value '4294967295'
Double Full: Size '8' Value '18446744073709551615'

From the result it is pretty easy to understand that the size of an enum will grow to 64bit when any of its values is greater than 32bit.

For our test we used g++ (GCC) 5.3.1 20160406 (Red Hat 5.3.1-6) on a 64bit Fedora 23.

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