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c++ - 类的 cout 中的内存地址而不是值

转载 作者：行者123 更新时间：2023-11-28 05:23:26 26 4
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<分区>

我正在尝试编写自己的简单转发列表实现。我想通过 cout << list[0] 访问元素。我写了下面的代码，但我得到的不是值而是 x637c00539997 之类的东西。我做错了什么？我的代码还可以改进什么？

#include <iostream>
#include <assert.h>
#include <cstdio>
#include <cstring>
#include <memory>

using namespace std;

class myList{
public:

  class myListExceptionEmpty: public exception
  {
  public:
    virtual const char* what() const throw()
    {
      return "EMPTY";
    }
  };

  void push_back(int valve);
  int getSize();
  bool isEmpty();
  void removeFirst();
  void remove(int x);
  void dump();
  void pop_front();
  struct elem
  {
    std::shared_ptr<elem> next;
    int val;
  };
  class proxy
  {
  public:
    std::shared_ptr<myList::elem>  position;
    proxy(std::shared_ptr<myList::elem> pos)
    {
      position = pos;
    }
  };
  std::shared_ptr<myList::proxy> operator[](int position);

private:
  std::shared_ptr<elem> start;
  std::shared_ptr<elem> getLastElement();
  std::shared_ptr<proxy> current;
  int size = 0;


};

ostream& operator<<(std::ostream& os, myList::proxy& obj)
{
      os << obj.position->val;
      return os;
}

shared_ptr<myList::proxy> myList::operator[](int position)
{
  std::shared_ptr<elem> p = start;
  for(int i=0;i<position;i++)
  {
    p = p->next;
    if (p == NULL) throw std::out_of_range("out");
  }
  //cout << p->val;
  std::shared_ptr<proxy> tmp(new myList::proxy(p));
  current = tmp;
  return current;
}

std::shared_ptr<myList::elem> myList::getLastElement()
{
    std::shared_ptr<elem> p = start;
    while(p->next != NULL ) p = p->next;
    return p;
}

bool myList::isEmpty()
{
  return size;
}

void myList::dump()
{
  std::shared_ptr<elem> x = start;
  while (x != NULL)
  {
      cout << x->val << endl;
        x = x->next;
  }
}

void myList::push_back(int valve)
{
  std::shared_ptr<elem> p, n(new elem());
  n->next = NULL;
  n->val = valve;
  p = start;
  if(p != NULL)
  {
     while(p->next != NULL ) p = p->next;
     p->next = n;
  }
  else start = n;
  size++;

}

void myList::remove(int x)
{
  if (size == 0) throw myListExceptionEmpty();
  std::shared_ptr<elem> p, prv;
  p = start;
  while(p->next != NULL)
  {
    if (p->val == x)
    {
      prv->next = p->next;
      size--;
    }
    prv = p;
    p = p->next;
  }
}

void myList::pop_front()
{

  if (size == 0) throw myListExceptionEmpty();
  std::shared_ptr<elem> p, prv;
  p = start;
  while(p->next != NULL)
  {
    prv = p;
    p = p->next;
  }
  prv->next = NULL;

}
void myList::removeFirst()
{
  if (size == 0) throw myListExceptionEmpty();
  std::shared_ptr<elem> p;
  p = start;
  cout << start->val << endl;
  if(p!= NULL)
  {
    start = p->next;
  }
  size--;

}

int myList::getSize()
{
  return size;
}

int main()
{
  myList array;
  int size;
  cin >> size;

  char a;
  int tmp;
  for (int i=0; i<size; ++i) {
    std::cin >> a;
    if (a == 'D')
    {
      try{
      array.removeFirst();
    }
    catch (myList::myListExceptionEmpty &e)
    {
      cout << e.what() << endl;
    }
    }
    else if (a == 'A')
    {
        int tmp;
        std::cin >> tmp;
        array.push_back(tmp);
        cout << "elem" << array[0];
    }
    else if (a == 'S') cout /*<< "Size:"*/ << array.getSize() << endl;
  }

}

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