从不同的类访问向量对象

Question

I created a vector with Pointers and I create new Objects from the class DigOut derived from Modul in one method called

BOOL Cbeckhoff_frontendDlg::OnInitDialog()
{
//...
std::vector<Modul*> arrDigOut;
arrDigOut.push_back(new DigOut(IDC_CHECK1, this,"GVL.DigOut1",pAddr));
//...
for(iNumDO = 0;iNumDO<1;iNumDO++) arrDigOut[iNumDO]->InitCheck(this);
//...
}

How can I access the vector from a different method like:

void Cbeckhoff_frontendDlg::OnBnClickedButton3()
{
for(iNumDO = 0;iNumDO<1;iNumDO++) arrDigOut[iNumDO]->SetID();
}

I thought about using public pointers or setters and getters,
but I don't get to create membervariables like this:

std::vector<Modul*> *   parrDigOut;

where it's complaining, that Modul is not declared.

Answer 1

如果我正确理解，请将其公开，并在其前面添加以下行：

class Modul;

Answer 2

Your example gives the impression you are declaring the vector at function scope. Its lifetime ends at the end of the function call (and all memory is leaked). Store it as a class member and a member functions begin and end that forward to the begin and end member functions of the vector . Possibly wrap them in a dereference_iterator to hide the fact that they are pointers.

class foo {
public:
  foo() { 
    // add things to s_
  }

  ~foo() { 
    // dont forget to delete everything in s_
  }
  typedef std::vector<my_stuff*>::iterator iterator;
  typedef std::vector<my_stuff*>::const_iterator const_iterator;
  iterator begin() { return s_.begin(); }
  iterator end() { return s_.end(); }
  const_iterator begin() const { return s_.begin(); }
  const_iterator end() const { return s_.end(); }

  // or to hide the pointers
  typedef boost::indirect_iterator< std::vector<my_stuff*>::iterator > iterator;
  iterator begin() { return boost::make_indirect_iterator(s_.begin()); }
  iterator end() { return boost::make_indirect_iterator(s_.end()); }
private:
  std::vector<my_stuff*> s_;
};

Answer 3

You could define a member variable as you described. On top of the class declaration just provide a forward declaration,

class Modul;

This is to let the compiler know that such a class is going to get defined somewhere down the line.

The member variables need not be public as it is accessed from another function in the same class.

And just declare the member as:

std::vector<Modul*>   parrDigOut; //No need of pointers

However, you could think of using a smart pointer to make sure that it gets deleted when the parent class gets out of scope