friend

My question is in regards to friend functions as well as overloading the << and >>. From my understanding I thought friend functions could (and should) access private member variables directly. However in the case I have here the compiler would only accept my .cxx file when I used "get" functions to obtain each private variable. Here is my header file class BigNum public: // CONSTRUCTORS and DESTRUCTORS BigNum(); BigNum(int num, size_t optional_base = 10); BigNum(const char strin[], size_t optional_base = 10); // MEMBER FUNCTIONS size_t get_digit(size_t index) const; size_t get_used() const;

I want tot send a friend request using the Facebook Android SDK. I'm currently using this code (which I got from here ): Bundle parameters = new Bundle(); parameters.putString("APP_ID","USERNAME"); facebook.dialog(this, "friends", parameters, this); where APP_ID is the Facebook ID of my app and USERNAME is the username of the friend I want to add. This leads to the following error: API Error Code:100 Invalid parameter The parameter id is required I thought the id parameter meant the APP_ID. I have gone through the relevant documentation regarding dialogs at http://developers.facebook.com/docs

Let us define f , as a friend function of S , inside the declaration of S : struct S { friend void f() {} }; I cannot find a way to call f . Is it true, then, that such an inline friend function can only be called with argument-dependant lookup ? struct S { friend void f() {} friend void g(S const&) {} } const s; int main() { // f(); // error: 'f' was not declared in this scope // S::f(); // error: 'f' is not a member of 'S' g(s); // S::g(s); // error: 'g' is not a member of 'S' } Bonus: what if I want to get a function-pointer/ std::function /lambda to g ? Is it true, then, that such an

Does a subclass inherit, the main class' friend associations (both the main class' own and other classes friended with the main class)? Or to put it differently, how does inheritance apply to the friend keyword? To expand: And if not, is there any way to inherit friendship? I have followed Jon's suggestion to post up the design problem: C++ class design questions Friendship is not inherited in C++. The standard says (ISO/IEC 14882:2003, section 11.4.8): Friendship is neither inherited nor transitive. friend only applies to the class you explicitly make it friend and no other class. http://www

What is the fully qualified name of a friend function defined inside of a class? I recently saw an example analogous to the following. What is the fully qualified name of val() below? #include <iostream> namespace foo { class A { int x; public: A(int x = 0) : x(x) { } friend int val(const A &a) { return a.x; } }; } int main() { foo::A a(42); // val() found using ADL: std::cout << val(a) << std::endl; // foo::val(a); // error: 'val' is not a member of 'foo' // foo::A::val(a); // error: 'val' is not a member of 'foo::A' return 0; } Is argument-dependent lookup the only way val() can be found?

In the beautiful answer to the copy-and-swap-idiom there is a piece of code I need a bit of help: class dumb_array { public: // ... friend void swap(dumb_array& first, dumb_array& second) // nothrow { using std::swap; swap(first.mSize, second.mSize); swap(first.mArray, second.mArray); } // ... }; and he adds a note There are other claims that we should specialize std::swap for our type, provide an in-class swap along-side a free-function swap, etc. But this is all unnecessary: any proper use of swap will be through an unqualified call, and our function will be found through ADL. One function

having a little architectural trouble here. In C++, we have the notion of 'friends,' where such friend classes can access private members. So, I'm deving a Java app and trying to adhere to the MVC architecture. I've got a controller class that manages graph connectivity between 'map_objects.' I'd like to hide the function in the DTO 'map_objects' that actuall sets up these connectivities, by using this controller class. (Ie, even if the controller class implements the required functionality of setting up connectivities, the 'users' can still access setter/getter functions in the the DTO