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请耐心等待,因为我是自学 C++ 的,并且我将有限的额外时间花在工作上以尝试更多地了解它(我白天是一名化学工程研究员)。

我有一个非常简单的目标: 1. 制作一个大小安全的容器来存储一长串浮点数。2. 制作该容器的专用版本,用作矩阵。

到目前为止,根据对我在这里提出的各种问题的一些反馈,我得出的结论是:

template<typename T>
class VectorDeque
{
public:

  void resize_index(unsigned int index) {
    if ( my_container == VECTOR ) {
      try {
        my_vector.resize(index);
        my_container = VECTOR;
      }
      catch(std::bad_alloc &e) {
        my_deque.resize(index);
        my_container = DEQUE;
      }
    }
    else if ( my_container == DEQUE ) {
      my_deque.resize(index);
    }
  }

  T operator[](unsigned int index) { 
    T ret_val;
    if ( STORAGE_CONTAINER == VECTOR ) {
      ret_val = my_vector[index];
    }
    else if ( STORAGE_CONTAINER == DEQUE ) {
      ret_val = my_deque[index];
      }
  }
private:
  enum STORAGE_CONTAINER { NONE, DEQUE, VECTOR };

  std::vector<T> my_vector;
  std::deque<T> my_deque;
  STORAGE_CONTAINER my_container;

  T& get(int index) { 
    T temp_val;
    if(my_container == VECTOR) {
      temp_val = my_vector[index];
    }
    else if(my_container == DEQUE) {
      temp_val = my_deque[index];
    }

    return temp_val;
  }

};

template<typename T>
class VectorDeque2D: public VectorDeque<T>
{
public:

  template<typename T>
  class VectorDeque2D_Inner_Set
  {
    VectorDeque2D& parent;
    int   first_index;
  public:
    // Just init the temp object
    VectorDeque2D_Inner_Set(My2D& p, int first_Index) : 
      parent(p), 
      first_Index(first_index) {} 
    // Here we get the value.
    T& operator[](int second_index)  const 
    { return parent.get(first_index,second_index);}   
  };

  // Return an object that defines its own operator[] that will access the data.
  // The temp object is very trivial and just allows access to the data via 
  // operator[]
  VectorDeque2D_Inner_Set<T> operator[](unsigned int first_index) { 
    return  VectorDeque2D_Inner_Set<T>(*this, first_index);
  }

  void resize_index_second(unsigned int second_index) {
    if ( my_container == VECTOR ) {
      try {
        for (unsigned int couter=0;couter < my_vector.size(); counter++) {
          my_vector[counter].resize(second_index);
        }
        my_container = VECTOR;
      }
      catch(std::bad_alloc &e) {
        for (unsigned int couter=0;couter < my_deque.size(); counter++) {
          my_deque[counter].resize(second_index);
        }
        my_container = DEQUE;
      }
    }
    else if ( my_container == DEQUE ) {
      for (unsigned int couter=0;couter < my_deque.size(); counter++) {
        my_deque[counter].resize(second_index);
      }
    }
  }

  void resize(unsigned int first_index,
          unsigned int second_index) {
    if ( my_container == VECTOR ) {
      try {
        my_vector.resize(first_index);
        for (unsigned int couter=0;couter < my_vector.size(); counter++) {
          my_vector[counter].resize(second_index);
        }
        my_container = VECTOR;
      }
      catch(std::bad_alloc &e) {
        my_deque.resize(first_index);
        for (unsigned int couter=0;couter < my_deque.size(); counter++) {
          my_deque[counter].resize(second_index);
        }
        my_container = DEQUE;
      }    
    }
    else if ( my_container == DEQUE ) {
      my_deque.resize(first_index);
      for (unsigned int couter=0;couter < my_deque.size(); counter++) {
        my_deque[counter].resize(second_index);
      }
    }
  }
private:
  enum STORAGE_CONTAINER { NONE, DEQUE, VECTOR };

  friend class VectorDeque2D_Inner_Set;

  std::vector<std::vector<T> > my_vector;
  std::deque<std::deque<T> > my_deque;
  STORAGE_CONTAINER my_container;

  T& get(int first_index,int second_index) { 
    T temp_val;
    if(my_container == VECTOR) {
      temp_val = my_vector[first_index][second_index];
    }
    else if(my_container == DEQUE) {
      temp_val = my_deque[first_index][second_index];
    }

    return temp_val;
  }

};

通过这个实现,我尝试:
1.向包装器的用户提供两个访问选项(“.get(x,y)”和“[x][y]”)
2.通过使用基于包装的类来最大化重用然后继承它来制作矩阵。
3.解决连续内存限制达到时从vector过渡到deque的问题。

这似乎是一个不错的解决方案?建议?

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2 回答 2

2

你看过Boost::Matrix吗?该库中已经构建了很多数值和线性代数的东西。

编辑:

在阅读了关于在达到大小限制时从向量过渡到双端队列的评论后,请使用deque. 像这样变得“花哨”会降低你的工作效率。专注于手头的问题,让收藏担心内存。双端队列对于大型数组来说非常快,并且与向量相比,只有在释放内存时才会受到影响。

于 2010-09-23T19:10:16.170 回答
0

对我来说,在一次使用期间在两者之间进行转换似乎不太值得。

如果您想通过自己滚动来执行此操作,您可以定义第二个模板参数,该参数允许在编译时指定容器类型。那么你就不需要两个vectordeque作为成员,类型切换代码就消失了。

template<typename T, typename CONTAINER>
class VectorDeque
{
// snip
private:
  CONTAINER<T> _storage;
};
于 2010-09-23T19:07:10.237 回答