Question

这个项目的最后一大障碍，我希望你们能帮助我，因为我再次陷入困境。我正在研究的是一个动态分配的模板化容器，所有代码都是从头开始使用常量迭代器编写的，以及一个随机迭代器，它以索引数组的形式生成排列。到目前为止，我已经得到它来正确生成索引，但我不确定如何让随机迭代器使用索引数组移动它们。对于随机迭代器，我认为我的++运算符存在问题，但我完全不确定该怎么做才能使它正确迭代。以下是一些片段：

// Implementation of the rand_iterator method when provided a seed  by   
// the user. rand_iterator takes a pointer to a container object, and the seed // as parameters.
template <class T>
typename sorted<T>::rand_iterator sorted<T>::rndbegin(unsigned seed){
  return rand_iterator(this, seed);
}

// Implementation of the const iterator pre-incrementer.
template <class T>
typename sorted<T>::const_iterator sorted<T>::const_iterator::operator++(){ ++m_current; return *this; }


// This is what my rndbegin looks like at the moment.
// Implementation of the rand_iterator rndbegin method.
template <class T>
typename sorted<T>::rand_iterator sorted<T>::rndbegin(){
  sorted<T>::rand_iterator newrand(this);
  return newrand;
}

// Implementation of the non-default rand iterator constructor given 
// a user-defined seed.
template <class T>
sorted<T>::rand_iterator::rand_iterator(sorted<T>* srtdPtr, unsigned seed){

  int j;
  m_rsize = srtdPtr->m_size;

  // Set up the random seed.
  // Allocate memory for m_random.
  srand(seed);
  m_random = new int[m_rsize];

  // Fill the randomized array with values.
  for (int i = 0; i < srtdPtr->m_size; i++)
    m_random[i] = i;

  // Randomize the values.
  for (int i = 0; i < srtdPtr->m_size; i++){

    T temp;

    j = rand() % (srtdPtr->m_size);
    temp = m_random[i];
    m_random[i] = m_random[j];
    m_random[j] = temp;
  }

  // Just testing to make sure the random array
  // is set up properly; it is. 
  cout << "Random seed test:" << endl;
  for (int i = 0; i < srtdPtr->m_size; i++)
    cout << m_random[i] << " ";
  cout << endl;

  m_current = 0;
  m_randPtr = srtdPtr;
}

// Implementation of the dereference operator.
template <class T>
const T& sorted<T>::rand_iterator::operator*(){
  return m_randPtr->m_data[m_random[m_current]];
}

// Some code from main that's causing an issue.
// ritr3 was already created and tested.
sorted<int>::rand_iterator ritr5(ritr3);

cout << "Printing copy constructed random index array - should print: 5 16 1 7 9 17 7 4 6" << endl;
cout << "Actually prints: " << endl;
for (ritr5 = x.rndbegin(4242); ritr5 != x.rndend(); ritr5++)
  cout << *ritr5 << " ";
cout << endl;

Answer 1

让m_current成为m_crandom的索引，让它从0更改为n，然后m_crandom[m_current]将成为改组后的索引实际的数据数组。

这是一个显示基本想法的例子：

http://coliru.stacked-crooked.com/a/47b28c0be0bcd027

创建随机迭代器（置换）

1 个答案: