#include <iostream>

struct Foo {
    Foo(std::string const& x) : data(x) {}

    std::string data;
};

int main()
{
    std::string a("Hello");
    Foo foo(a);
    Foo* msg = &foo;
    string str = msg->data;
    str = "World";

    std::cout << a << "\n" << str << std::endl;
}

Hello
World