Question

我是复制构造函数的新手，所以也许我只是不知道它们是如何工作的，但我不明白为什么这不起作用。以下是构造函数的实现：

Heap::Heap(void){ // New empty Heap with default capacity.
   h_capacity = 10;
   A = new int[h_capacity];
   h_size = 0;
}

Heap::Heap(int c){ // New empty Heap with capacity c.
   A = new int[c];
   h_capacity = c;
   h_size = 0;
}

Heap::Heap(int * B, int s, int c){ // New Heap with capacity c containing first s elements of B.
   A = new int[c];
   h_capacity = c;

   A = new int[h_capacity];

   for (int i = 0; i < s; i++){
      (A[i]) = B[i];
   }

   h_size = s;
}

Heap::Heap( const Heap & H ){ // Copy constructor.
   h_capicity = H->h_capicity;
   h_size = H->h_size;

   A = new int[h_capicity];

   for (int i = 0; i < h_size; i++){
      (A[i]) = H->A[i];
   }

这是头文件：

#include <iostream>
using namespace std;

class Heap{

public:
      // Constructors and Destructor
      Heap();  // New empty Heap with default capacity.
      Heap(int c); // New empty Heap with capacity c.
      Heap(int * B, int s, int c); // New Heap with capacity c containing first s elements from B.
      Heap( const Heap & H ); // Copy constructor.
      ~Heap(); // Destructor.

      // Size and Capacity
      bool empty() {return h_size == 0;}; // True iff Heap is empty.
      int size(){ return h_size ;}; // Current size of Heap.
      int capacity(){ return h_capacity ;}; // Current capacity.

      // Operators
      Heap operator+( const Heap & H ) const; // New Heap with combined contents and capacity of operands.

      // Modifiers
      void insert(int x); // Insert element x.
      int extract_min(); // Remove and return the minimum element.

      // Display
      void display(); // Print a string representation of the heap contents to standard out.

private:
      int* A ; // Array containing heap contents.
      int  h_capacity ; // Max number of elements (= size of A).
      int h_size ; // Current number of elements.

      void trickle_up(int i);// Repairs ordering invariant after changing root.
      void trickle_down(int i);// Repairs ordering invariant after adding a leaf.
      void make_heap();// Restores ordering invariant to entier contents.
};

但是当我编译时，我得到：

heap.cpp: In copy constructor ‘Heap::Heap(const Heap&)’:
heap.cpp:34: error: ‘h_capicity’ was not declared in this scope

Answer 1

您将h_capacity拼错为h_capicity。

此外，正如其他人所指出的，您需要修复->的使用情况。编译器会在适当的时候抱怨这一点。：）

P.S。不要忘记定义赋值运算符。

P.P.S。将Heap(int c);标记为explicit可能是有意义的，以防止从int到Heap的不必要的隐式转换。

Answer 2

h_capicity = H->h_capicity;

错误容量

int  h_capacity

然后你会在访问H（你正在复制为指针的堆对象）时得到一个错误它是一个参考，所以它应该是：

h_capacity = H.h_capacity;

查找使用->代替.

的更多问题

Answer 3

你宣布了

int  h_capacity ; // Max number of elements (= size of A).

你正在使用

h_capicity = H->h_capicity;

为什么C ++中的这个拷贝构造函数不能编译？

3 个答案: