How can i pass the this stl list to the fun function and access the struct in the function?

Question

3.00/5 (2 votes)

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i have an base class like this

C++

class Base
    {
    public:
    virtual void fun() const =0;
    };

Derived class like this :

C++

class Derived:public Base
  {
  virtual void fun()
  {
  //implemtation of fun
  }
  };

I had an global structure

C++

struct Mystruct
  {
  int a;
  char *b;
  }MYSTRUCT;

I added the structure in list stl as

C++

std::list< MYSTRUCT* > SS1;
     List  = new MYSTRUCT;
        vector<MYSTRUCT*>SS;
    SS.push_back( List);

Now can i pass the this stl list to the fun function and access the struct in the function?

Posted 30-Oct-12 9:46am

Tarun Batra

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Comments

Richard MacCutchan 30-Oct-12 17:01pm

You need to declare a version of fun() that takes a parameter of the requested type. Once again I recommend you spending some more time reading your C++ programming manuals.

Sergey Alexandrovich Kryukov 30-Oct-12 22:17pm

Best answer so far. And also, pass the parameter by reference, as a constant reference -- one more topic for reading.
--SA

Richard MacCutchan 31-Oct-12 4:46am

Thanks. Given all the posts from this person, he seems to be trying to learn C++ and develop a complex application at the same time, just by asking questions here.

Sergey Alexandrovich Kryukov 31-Oct-12 10:44am

This is amazing. This person is not the only one. And it goes nowhere, absolutely non-productive.

However, I recently noticed one guy why intensively trying to learn .NET the same way, by asking question, in somewhat effective way, asking simple but right-to-the-point, deep question. This is a rare case when a person has considerable intellect and learning abilities, which... could be used way more effectively. It already took a lot of time and nerve from experts...

--SA

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Eugen Podsypalnikov · Answer 1 · 2012-10-30T11:06:00

// Now can i pass the this stl list to the fun function and access the struct in the function?
Please observe the elements navigation in the Test-class :) :

C++

struct MS {
  bool  bDataOwner;
  int   iData;
  char* pData;
  
  MS() : bDataOwner(false), iData(0), pData(NULL) {}
  ~MS() { if (bDataOwner && pData) delete pData /*use free(pData) for C allocations*/; }
};

typedef std::list<ms*> lstPMS;
typedef lstPMS::iterator iterPMS;

class lstOwnerMS : private lstPMS
{
public:
  virtual ~lstOwnerMS() { Empty(); }

  void AddData(const MS* pMS) {
    lstPMS::push_back(pMS);
  }

  iterPMS GetHeadPosition() const {
    return lstPMS::begin() < lstPMS::end() ? lstPMS::begin() : NULL;
  }

  MS* GetNext(iterPMS& iter) const {
    MS* pResult(NULL);
    if (iter < lstPMS::end()) {
      pResult = iterPMS;
      iterPMS++;
    } else {
      iterPMS = NULL;
    }
    return pResult;
  }

  void Empty() {
    while (!lstPMS::empty()) {
      delete lstPMS::front();
      lstPMS::pop_front();
    }
  }
};

class IBase
{
public:
  virtual void ProcessPMSList(lstOwnerMS& lst) const = 0;
};

class Test : public IBase
{
public:
  virtual void ProcessPMSList(lstOwnerMS& lst) const
  {
    // elements navigation
    iterPMS iter(lst.GetHeadPosition());
    while (iter) {
      MS* pMs(lst.GetNext(iter));
      if (pMs) {
        cout << pMS->iData << " ";
      }
    }
  }
};

int main()
{
  lstOwnerMS lstOwner;
  lstOwner.AddData(new MS);

  MS* pMS(new MS);
  pMS->bDataOwner = true;
  pMS->pData = new char[2];
  strcpy_s(pMS->pData, 2, ".");
  lstOwner.AddData(pMS);

  Test test;
  test.ProcessPMSList(lstOwner);
  
  return 0;
};