using std::initializer_list as a member variable [duplicate]

Question

I have a class A that takes an initializer_list and stores it as a member variable.

class A
{
public:
    A(std::initializer_list<std::string> il) :
        m_il(il)
    {}

    std::initializer_list<std::string> m_il;
};

Another class B has A as a member variable that is default initialized using the initializer_list

class B
{
public:
    B()
    {
        std::cout << *m_a.m_il.begin() << std::endl;
    }

    A m_a { "hello", "bye" };
};

Now when I run this code in main, it prints nothing.

int main()
{
    B b;
}

Why did the code above not print hello? Is my usage of std::initializer_list incorrect?

Answer 1

Copying a std::initializer_list does not copy its underlying objects. It's not meant to be used as a container. What you should be doing instead is storing it in something else, like a std::vector:

class A
{
public:
    A(std::initializer_list<std::string> il) :
        m_il(il)
    {}

    std::vector<std::string> m_il;
};