Is it possible in class C to perform the calculation int a / int b and write the result in a variable of class C int c ?

 class A { int a = 5; }; class B { int b = 10; }; class C { friend class A; friend class B; int c; };
  • Is it possible to make int c = int a / int b in class C constructor? - Maryna Said
  • You changed the code and thus distorted the text of the question and made the wrong answer - this is not good. In fact, you wrote the answer instead of a question. Please return the original code, and leave the code that you wrote according to your answer somewhere separately, for example, on pastebin. - andreymal

3 answers 3

If you are interested in the question of whether a friendly class can use private class names, whose friend it is, then yes — for example:

 #include <iostream> using std::cout; class C; // вначале обьявите class A { friend class C; int a; public: A() : a(10) { } // в конструкторе инициализировать, а не так как вы сделали }; class B { friend class C; int b; public: B() : b(5) {} }; class C { int c; // с это не C, поэтому можно public: C() { A t; B k; c = ta/kb;} // нужно создавать обьекты типов int get_res() const { return c; } }; int main() { C g; std::cout << g.get_res(); return 0; }
  • does not recognize t (where A is t) and k (where B k) - Maryna Said
  • one
    you wrote something wrong, be careful (for example, I left an extra, but familiar to me, line for you), check again - AR Hovsepyan

You see, if I say that you are my friend - you are not letting me out of my statement from me to spend the night?

But I sort of should, once stated that you are my friend ...

This is how you have - class C stated that he is a friend of A and B , so he trusts his insides to them :) And they did not express such confidence to him.

Agree, it would be too insecure - so any class, any function could get access to any hidden fields - just announcing your desire ...

  • oh I'm a little confused :) made changes) and so? - Maryna Said
  • 2
    It is better not to make such changes in the SAM question. It is better to upload to a hosting code like pastebin - because with edits like yours, people who read this question much later will not understand its essence. Suggested edit, returning question to pre-edit status (code only). Also slightly corrected formatting, improving readability. - handicraftsman
  • And in fact, the author of the answer explained everything correctly - your new version should work fine. - handicraftsman
  • class A cannot have class C as a friend, since it is not in scope ... and cannot be initialized in a class this way (int a = 5;) - AR Hovsepyan
  • one
    @Ancient, yes, but the author of the question does not have this announcement - AR Hovsepyan

In your example, there is no a and there is no b .

In your example, there are only non-static fields of the classes A::a and B::b . Non-static class fields do not exist physically by themselves. Non-static class fields exist only inside objects (instances) of these classes, only together with these objects. Therefore, until you create objects of these classes, there will be no a and b .

If you have an instance of aa class A and an instance of bb class B , then you can easily calculate the value of aa.a / bb.b if you have the appropriate access rights. But as long as you do not have such instances, there is nothing to talk about, for no a and b exist.

In your code, I do not see the slightest hint that class C works with some instances of classes A and B And without instances of any a and b and can not speak.