Question

Given the following C++11 code

enum class Foods {
  Apple,
  Pear,
  Banana
};

will

std::cout << (unsigned int)Foods::Apple << std::endl;

output 0?

This is true for MSVC 2012 and gcc 4.7.0 however I’m more interested in what the C++11 standard specifies we may rely on. That is, can portable code depend on enumerations defaulting to 0 for the value of the first item?

Answer 1

Yes, they are. It’s in §7.2/2:

[…] If the first enumerator has no initializer, the value of the corresponding constant is zero. An enumerator-definition without an initializer gives the enumerator the value obtained by increasing the value of the previous enumerator by one.

This section covers both enum class declarations and regular enum declarations