Question

Is this the correct way to typedef an inner class in C++?

class Foo
{
public:
    struct A
    {
        typedef bool Type;
    };

    struct B
    {
        typedef int Type;
    };

    typedef struct Foo::nested;
};

The code compiles under Visual Studio 2008 but I’m not sure if it is indeed a typedef of a nested class, or whether the standard permits it.

Answer 1

Not sure what you are after. If you’d like to typedef one of the existing nested structures, try:

typedef struct Foo::A nested;

Most likely you want to place the typedef outside of the Foo struct in this case — you can already access A from within.

If you wanted to create a typedef inside Foo for a nested type of another struct, you could do this:

typedef struct Bar::nested myNested;

Then you can refer to it as Foo::myNested from outside as well, as long as you declared the typedef public.