Help needed!!!

[sergelaurent]

I have got 2 ".h" file containing 2 class. There are some functions in the second class that I want to use in the first one. How can I do this? Can I use "friend"? Does it works when the 2 class are not in the same ".h" file?

 

[ArkM]

Does not matter friend or alien, the only demand: class must been declared (textually) before using its members. For example, if C1 member functions (implemented in separate .cpp file) use C2 members, no .h including order dependencies:

// c1.h:
class C1 { /* declarations only */ };
// c2.h:
class C2 { /* declarations only */ };
//c1.cpp
#include "c1.h"
#include "c2.h"
... C1:func_member()
{
...
   C2 c2;
   c2.f(...);
}

If you want C2 as a friend of C1, you may use incomplete declaration of C2 in c1.h:

// c1.h:
class C2; // that's all; declare C2 in another header
class C1
{
...
  friend class C2; // OK
...
};

 

[cpjust]

You only need to declare classes as friends if you want those classes to have access to non-public member functions. If the functions are public, anyone in the world can call them as long as they include the header file...