在 C++ 中将类实例添加到对象层次结构时出现问题

Posted 2023-02-21

【中文标题】在 C++ 中将类实例添加到对象层次结构时出现问题

【英文标题】：Problems adding a class instance to a hierarchy of objects in C++

【发布时间】：2019-11-13 12:51:28

【问题描述】：

在我们的项目中，我们需要创建三个类：客户、活动和广告。每个客户都有一个营销活动向量，每个营销活动都有一个广告向量：

客户 -> 活动 -> 广告

当我们尝试将广告实例添加到 给定客户的广告系列。

当我们尝试将广告添加到给定的广告系列时，我们从未看到它 实际添加广告。广告数量保持不变。

我们都是 C++ 新手，不知道如何通过引用来解决这个问题，我们认为这与问题有关。

客户类：

#pragma once
#include <vector>
#include <cstdio>
#include <string>
#include "campaign.h"

using namespace std;

class Customer

    string name;
    int id;
    vector<Campaign> campaigns;
public:


    Customer(string name, int id)
    
        this->name = name;
        this->id = id;
    

    string GetName()
    
        return name;
    

    void SetName(string name)
    
        this->name = name;
    

    int GetId()
    
        return id;
    

    void SetId(int id)
    
        this->id = id;
    

    bool AddCampaign(Campaign campaignObject)
    
        campaigns.push_back(campaignObject);
        return true;
    

    bool CommitAdvertisement(Ad ad, int campaignID)
    
        for (int i = 0; i < campaigns.size(); i++)
        
            if (campaigns[i].GetId() == campaignID)
            
                campaigns[i].CommitAdvertisement(ad);
                return true;
            
        
        return false;
    

    bool hasActiveCampaigns()
    
        for (Campaign i : campaigns)
        
            if (i.IsActive())
            
                return true;
            
        
        return false;
    

    vector<Campaign> GetAllCampaigns()
    
        return campaigns;
    

    vector<Ad> GetAllAdsForCampaign(int campaignID)
    
        for (int i = 0; i < campaigns.size(); i++)
        
            if (campaigns[i].GetId() == campaignID)
            
                return campaigns[i].GetAllAds();
            
        
    
;

广告系列类：

#pragma once
#include <ctime>
#include <string>
#include <vector>
#include <iostream>
#include <exception>
#include <ctime>
#include "Ad.h"

using namespace std;


class Campaign

    string name;
    int id;
    time_t fromDateTime;
    time_t toDateTime;
    float campaignCost;
    vector<Ad> ads;

public:
    Campaign(time_t fromDateTime, time_t toDateTime, int id, string name, float campaignCost)
    
        this->fromDateTime = fromDateTime;
        this->toDateTime = toDateTime;
        this->id = id;
        this->name = name;
        this->campaignCost = campaignCost;
    

    time_t GetFromDateTime()
    
        return fromDateTime;
    

    void SetFromDateTime(time_t fromDateTime)
    
        this->fromDateTime = fromDateTime;
    

    time_t GetToDateTime()
    
        return toDateTime;
    

    void SetToDateTime(time_t toDateTime)
    
        this->toDateTime = toDateTime;
    

    int GetId()
    
        return id;
    

    void SetId(int id)
    
        this->id = id;
    

    string GetName()
    
        return name;
    

    void SetName(string name)
    
        this->name = name;
    

    float GetCampaignCost()
    
        return campaignCost;
    

    void SetCampaignCost(float campaignCost)
    
        this->campaignCost = campaignCost;
    

    bool IsActive()
    
        time_t now = time(NULL);

        if (fromDateTime <= now && toDateTime >= now)
        
            return true;
        
        return false;
    

    bool CommitAdvertisement(Ad ad)
    
        for (Ad i : ads)
        
            if (i.GetId() == ad.GetId())
            
                return false;
            
        
        ads.push_back(ad);
        return true;
    

    bool DeleteAdvertisement(int id)
    
        for (int i = 0; i < ads.size(); i++)
        
            if (ads[i].GetId() == id)
            
                ads.erase(ads.begin() + i);
                return false;
            
        
        return false;
    

    vector<Ad> GetAllAds()
    
        return ads;
    
;

广告类

#pragma once
#include <string>
#include <vector>
#include <iostream>
#include <exception>
#include "AdType.h"

using namespace std;

class Ad


private:

    string name;
    string adText;
    AdType adType; 
    int id;

public:

    Ad(string name, string text, int id, AdType type = AdType::PLAINTEXT)
    
        this->name = name;
        this->adText = text;
        this->id = id;
        this->adType = type;
    

    string GetName()
    
        return name;
    

    void SetName(string name)
    
        this->name = name;
    

    int GetId()
    
        return id;
    

    void SetId(int id)
    
        this->id = id;
    

    AdType GetType()
    
        return adType;
    

    void SetType(AdType type)
    
        this->adType = type;
    

    string GetText()
    
        return adText;
    

    void SetText(string adText)
    
        this->adText = adText;
    
;

现在，我们已经成功地向给定客户添加了一个广告系列，并且能够添加 一个 广告实例，但不能再添加了。

这段代码 sn-p 显示了这种尝试：

    // Create a customer
    Customer *the_client = new Customer("Foobar Inc", 123);

    // Create a campaign
    Campaign *the_campaign = new Campaign(begin, end, 1234, "campaign_name", 123455.0f);

    // Create an ad
    Ad *the_first_ad = new Ad("First ad", "adtext", 12345656, AdType::PLAINTEXT);

    // create another ad
    Ad* the_second_ad = new Ad("Second ad", "adtext", 12345656, AdType::PLAINTEXT);

    // add the campaign to the customer
    the_client->AddCampaign(*the_campaign);

    // Add the ad to the customers' list of ads
    the_client->CommitAdvertisement(*the_first_ad, 1234);

    // Print out how many ads there are in the given campaign
    cout << "There are now " << the_client->GetAllAdsForCampaign(1234).size() << "ads int the campaign" << endl;

    // Add the second ad to the customers' list of ads
    the_client->CommitAdvertisement(*the_second_ad, 1234);

    // Again - print out how many ads there are in the given campaign
    cout << "There are now " << the_client->GetAllAdsForCampaign(1234).size() << "ads int the campaign" << endl;

很可能我们完全做错了，但我们非常欢迎任何指导。

【问题讨论】：

终生提示：检查返回值 ;-)。顺便说一句，由于尝试两次添加相同的广告可能是（意料之外的，在“不应该发生”的意义上）错误，因此可以考虑抛出异常。这使代码从错误检查和处理中变得杂乱无章（默认处理程序是 abort()）。

是的，当然。非常感谢，我去看看！

【参考方案1】：

CommitAdvertisement如果已经有相同id的广告，会返回false，添加失败。

这就是你正在做的事情。第一个和第二个广告的 id 都是 12345656。所以它按照你的要求做。

增加the_second_ad 的ID。

【讨论】：

哇，我觉得自己很愚蠢。这就是用新语言不停编码的日子所做的。愚蠢的复制粘贴。谢谢你的回答！