C++ Enumeration Iteration over an enum
Example
There is no built-in to iterate over enumeration.
But there are several ways
-
for
enumwith only consecutive values:enum E { Begin, E1 = Begin, E2, // .. En, End }; for (E e = E::Begin; e != E::End; ++e) { // Do job with e }
C++11
with enum class, operator ++ has to be implemented:
E& operator ++ (E& e)
{
if (e == E::End) {
throw std::out_of_range("for E& operator ++ (E&)");
}
e = E(static_cast<std::underlying_type<E>::type>(e) + 1);
return e;
}
-
using a container as
std::vectorenum E { E1 = 4, E2 = 8, // .. En }; std::vector<E> build_all_E() { const E all[] = {E1, E2, /*..*/ En}; return std::vector<E>(all, all + sizeof(all) / sizeof(E)); } std::vector<E> all_E = build_all_E();and then
for (std::vector<E>::const_iterator it = all_E.begin(); it != all_E.end(); ++it) { E e = *it; // Do job with e; }
C++11
-
or
std::initializer_listand a simpler syntax:enum E { E1 = 4, E2 = 8, // .. En }; constexpr std::initializer_list<E> all_E = {E1, E2, /*..*/ En};and then
for (auto e : all_E) { // Do job with e }
