C++ Operator overloading: assign A's attribute value of type B to a B object

Question

The std::string class allows assigning its internal value from different types, such as 'char', 'const char*' and 'std::string', with the help of this operator. Which operator is needed to be overloaded in order to achieve the following?

class A {
public:
    A(std::string value)
        : m_value(value)
    {
    }

    // A a = std::string("some value")
    A& operator=(const std::string value) {
        m_value = value;
    }

    // std::string someValue = A("blabla")
    ???? operator ????

private:
    std::string m_value;
};

After that, we should be able to access std::string's functions through the A object, for example:

A a("foo");

printf("A's value: %s \n", a.c_str());

Answer 1

You need to make it possible for class A to convert itself to type string .

This looks like:

class A
{
public:
    operator std::string() const { return m_value; }
};

After that, you can do this:

printf("A's value: %s \n", ((std::string)a).c_str());

---

Alternately, you can overload the -> operator:

class A
{
public:
    const std::string* operator->()const { return & m_value; }
}

printf("A's value: %s \n", a->c_str());

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