Class two has no member v error

I am new to C++ and I have a problem.I am trying to make to classes mutual friend,and accessing different members in one from the other one.I can't figure out what is that I do wrong.Here is what I have so far:

#ifndef HA_H_
#define HA_H_
#include"Ha2.h"
using namespace std;
class two;
class one{
public:
    int tip;
    in开发者_开发知识库t timp;
    one(int t) :tip(t){}
    friend class two;
};


#endif /* HA_H_ */

The second header:

#ifndef HA2_H_
#define HA2_H_
#include"Ha.h"
#include<vector>
class one;
class two{
public:
    vector<one> v;
   vector<int> x;
   inline void create_x(vector<one> v){
     // vector<one>::iterator it=v.begin();
      int i;
      for(i=0;i<v.size();i++){
          x.push_back(v.at(i).tip);
      }

   }

    friend class one;
};


#endif /* HA2_H_ */

And the main:

#include<vector>
#include<iostream>
#include"Ha.h"
#include"Ha2.h"
int main()
{
one o(3);
two x;
x.v.push_back(o);

x.create_x(x.v);
cout<< x.x.back();
}

And I get several errors like: class two has no member named 'v'

Any advice?Thank you.

---

main.cpp includes "Ha.h", which, before using namespace std;, includes "Ha2.h". Then, class two is defined, which declares v as a vector<one> without qualifying vector in the std namespace.

There is no need to include "Ha2.h" in "Ha.h", remove that, then qualify vector.

---

• Forward declarations are used when the class definition has pointers or references. And neither of the class definitions has them and so forward declarations are unnecessary.

• Also the headers has both forward declarations and it's corresponding header inclusion which voids the whole purpose of forward declarations.

• Include the headers and also the using directive in the source files.

• As of now, the program has no methods to test the purpose of friend and so this should at least make the program compile.

---

Ha.h header :

#ifndef HA_H_
#define HA_H_

    class two ;  // No pointers or references of two in one.
                 // So, remove it and place when you actually have
                 // a method taking reference of two.
    class one{
        public:
           int tip;
           int timp;
           one(int t) :tip(t){}
           friend class two;
    };

#endif /* HA_H_ */

Ha.cpp

#include "Ha2.h"  // Place this only when have a method accessing
                  // members of two. Else this is unnecessary.

#include "Ha.h"
using namespace std ;

Ha2.h

#ifndef HA2_H_
#define HA2_H_

    class one ;    // No pointers or references of one in two.
                   // So, remove it and place when you actually have
                   // a method taking reference of one.
    class two{
        public:
           vector<one> v;
           vector<int> x;
           inline void create_x(vector<one> v)
           {
               // vector<one>::iterator it=v.begin();
               int i;
               for(i=0;i<v.size();i++)
               {
                   x.push_back(v.at(i).tip);
               }
           }

    friend class one;
    };

#endif /* HA2_H_ */

Ha2.cpp

#include <vector>
#include "Ha.h"    // Place this only when have a method accessing
                   // members of two. Else this is unnecessary.

#include "Ha2.h"

using namespace std ;

// .....

main.cpp

#include <vector>  // Definitely need this because in the current unit, Ha2.h is
                  // included which has a data type of vector<int>

#include <iostream>

#include"Ha.h"
#include"Ha2.h"

using namespace std ; // vector and the other standard definitions are specified
                      // in std namespace
int main()
{
    one o(3);
    two x;
    x.v.push_back(o);

    x.create_x(x.v);
    cout<< x.x.back();
}

With the above modifications, you should get rid of errors. If any new errors pop up, post the exact error messages in your question.

---

Another alternative to remove the circular dependency is to make a separate header file, like decl.h or whatever you want it to be, and inside of that simply put the following lines:

#ifndef DECL_H_
#define DECL_H_

class one;
class two;

#endif DECL_H_

Then in Ha.h and Ha2.h remove the #include "Ha.h" and #include "Ha2.h" lines and replace them with #include "decl.h". Also remove the class one; and class two; declarations in Ha.h and Ha2.h, but keep the definitions of each respective class.

Now you won't have Ha.h depending on Ha2.h and vice versa.

Hope this helps,

Jason