c++ - Input from stream to enum type

Question

How to input from stream to enum type?

I can do it so

unsigned int sex = 0;
stream >> sex;
student.m_bio.sex = static_cast<Sex>(sex);

Otherwise?

Answer 1

inline std::istream & operator>>(std::istream & str, Sex & v) {
  unsigned int sex = 0;
  if (str >> sex)
    v = static_cast<Sex>(sex);
  return str;
}

If you want to ensure that the value is valid, you can do something like this:

enum Sex {
    Male,
    Female,
    Sex_COUNT
};

inline std::istream & operator>>(std::istream & str, Sex & v) {
  unsigned int sex = 0;
  if (!(str >> sex))
    return str;
  if (sex >= Sex_COUNT) {
    str.setstate(str.rdstate() | std::ios::failbit);
    return str;
  }
  v = static_cast<Sex>(sex);
  return str;
}