我的程序从指针列表中删除对象并添加到指针列表的问题答案

【问题标题】：Problems with my program deleting objects from pointer list and adding to pointerlist我的程序从指针列表中删除对象并添加到指针列表的问题
【发布时间】：2017-10-13 17:27:23
【问题描述】：

我想知道有人可以帮我完成我的程序吗？我的 dragon.cpp 文件有一些问题，我似乎无法创建不同类型的龙。

我还是 C++ 新手，不知道如何解决这些错误

更新

我从 dragon.cpp 中删除了第二个构造函数，现在我得到了新的错误。我还在 Dragon 类的头文件中添加了一个虚拟解构器。

错误

 Severity   Code    Description Project File    Line    Suppression State
Error   LNK2019 unresolved external symbol "class std::basic_ostream<char,struct std::char_traits<char> > & __cdecl operator<<(class std::basic_ostream<char,struct std::char_traits<char> > &,class DragonCave const &)" (??6@YAAAV?$basic_ostream@DU?$char_traits@D@std@@@std@@AAV01@ABVDragonCave@@@Z) referenced in function _main  main.obj    1   
Error   LNK1120 5 unresolved externals  Dragon.exe  1   
Error   LNK2019 unresolved external symbol "public: class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const & __thiscall Dragon::getName(void)const " (?getName@Dragon@@QBEABV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@XZ) referenced in function _main   main.obj    1   
Error   LNK2019 unresolved external symbol "public: void __thiscall DragonCave::accommodateDragon(class Dragon *)" (?accommodateDragon@DragonCave@@QAEXPAVDragon@@@Z) referenced in function _main  main.obj    1   
Error   LNK2019 unresolved external symbol "public: void __thiscall DragonCave::evictDragon(class std::basic_string<char,struct std::char_traits<char>,class std::allocator<char> > const &)" (?evictDragon@DragonCave@@QAEXABV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@@Z) referenced in function _main        main.obj    1   
Error   LNK2019 unresolved external symbol "public: __thiscall DragonCave::DragonCave(void)" (??0DragonCave@@QAE@XZ) referenced in function _main   main.obj    1

我的 main.cpp

https://pastebin.com/dKwuVPn7

我的龙.hpp

https://pastebin.com/cbJ2Z80D

我的dragon.cpp

#include "dragon.hpp"
 
#include <string>
#include <list>
#include <iostream>
 
/* Dragon class functions here*/
Dragon::Dragon(std::string const& name, size_t age, size_t size) {}
/* DragonCave class functions here*/
DragonCave::DragonCave() {
 
    std::cout << "Copy constructor called" << std::endl;
    for (auto i : d.dragons) {
        Dragon *c = i->clone();
        dragons.push_back(c);
    }
}
 
// Made for you, as it uses a tiny bit of dynamic memory here! You will see more of this in the next round.
DragonCave::~DragonCave()
{
    for (std::list<Dragon*>::iterator it = dragons.begin(); it != dragons.end(); it++)
        delete *it;
}
 
/* ChineseDragon class functions */
//Constructor here
 
ChineseDragon::ChineseDragon(std::string const& name, size_t age, size_t size) : Dragon(name, age, size) { }
 
void ChineseDragon::eat(std::list<Food>& food)
{
    for (std::list<Food>::iterator it = food.begin(); it != food.end();)
        if (it->type == PeopleFood)
        {
            std::cout << "Chinese dragon ate: " << it->name << std::endl;
            it = food.erase(it);
            size++;
        }
        else it++;
 
}
 
void ChineseDragon::hoard(std::list<Treasure>& treasures)
{
    for (std::list<Treasure>::iterator it = treasures.begin(); it != treasures.end();)
        if (it->type == Potions)
        {
            std::cout << "Chinese dragon received: " << it->name << std::endl;
            this->treasures.push_back(*it);
            it = treasures.erase(it);
        }
        else it++;
 
 
}
 
 
FantasyDragon::FantasyDragon(std::string const& name, size_t age, size_t size) : Dragon(name, age, size) { }
 
void FantasyDragon::eat(std::list<Food>& food)
{
    for (std::list<Food>::iterator it = food.begin(); it != food.end();)
        if (it->type == PeopleFood | People)
        {
            std::cout << "Fantasy dragon ate: " << it->name << std::endl;
            it = food.erase(it);
            size++;
        }
        else it++;
 
 
}
 
void FantasyDragon::hoard(std::list<Treasure>& treasures)
{
 
    for (std::list<Treasure>::iterator it = treasures.begin(); it != treasures.end();)
        if (it->type == Potions)
        {
            std::cout << "Fantasy dragon received: " << it->name << std::endl;
            this->treasures.push_back(*it);
            it = treasures.erase(it);
        }
        else it++;
 
}
 
 
/* MagicDragon class functions */
MagicDragon::MagicDragon(std::string const& name, size_t age, size_t size) : Dragon(name, age, size) { }
 
void MagicDragon::eat(std::list<Food>& food)
{
    for (std::list<Food>::iterator it = food.begin(); it != food.end();)
        if (it->type == Herbs)
        {
            std::cout << "Magic dragon ate: " << it->name << std::endl;
            it = food.erase(it);
            size++;
        }
        else it++;
}
 
void MagicDragon::hoard(std::list<Treasure>& treasures)
{
    for (std::list<Treasure>::iterator it = treasures.begin(); it != treasures.end();)
        if (it->type == Potions)
        {
            std::cout << "Magic dragon received: " << it->name << std::endl;
            this->treasures.push_back(*it);
            it = treasures.erase(it);
        }
        else it++;
}

【问题讨论】：

您在头文件和源文件中都实现了 Dragon 构造函数。你应该只做其中一个。
请提供minimal reproducible example 并将所有相关代码直接发布到问题中。因为您提供的一个文件中有很多不必要的代码。
@Galik 感谢您的关注，现在我遇到了新错误，我已经更新了问题。
这可能是您没有为其编写实现的函数列表 - 或者您可能给了它们错误类型的参数？

标签： c++ class c++11

【解决方案1】：

这些错误告诉您，您的某些函数缺少实现。特别是 operator<<(std::ostream& os, DragonCave const& cave)、Dragon::getName、DragonCave::accommodateDragon 和 DragonCave::evictDragon 已声明但从未定义。

最后一个错误是指DragonCave::DragonCave()，根据您发布的代码，它实际上是定义的。然而，它似乎曾经是一个复制构造函数，并且有一个变量d 突然出现。我怀疑这个错误与此有关。

【讨论】：