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c++ - 在 C++ 的构造函数中分配对象向量时出错

问题描述

我有这个代码：

#ifndef APPSYSTEM_H
#define APPSYSTEM_H
#include "Application.h"

#include <iostream>
#include <exception>
#include <vector> 

using namespace std;

class AppSystem{
private:
    vector<Application &> &ApplicationVector;
public:
    AppSystem(vector<Application &> &); //AppSystem Constructor
    AppSystem(const AppSystem &); //Copy constructor
    void setApplicationVector(vector<Application &> &); //set the AppSystem's Application Vector
    vector<Application &> getApplicationVector(); //get the AppSystem's Application Vector        
    virtual ~AppSystem(); //Destructor
};


#include "AppSystem.h"
#include <iostream>

//AppSystem Constructor
AppSystem::AppSystem(vector<Application &> &appSystemVector){
    ApplicationVector = appSystemVector;
} 

//Copy constructor 
AppSystem::AppSystem(const AppSystem &appSystem){
    ApplicationVector = appSystem.ApplicationVector;
}

//set the AppSystem's Application Vector
void AppSystem::setApplicationVector(vector<Application &> &applicationVector){
    this->ApplicationVector = applicationVector;
}

//get the AppSystem's Application Vector       
vector<Application &> AppSystem::getApplicationVector(){
    return this->ApplicationVector;
}

//Destructor
AppSystem::~AppSystem(){
    cout << "Destroying AppSystem Object " << endl; 
}


#include "AppSystem.h"
#include "Application.h"
#include "ApplicationConstructor.h"
#include "UserOpinion.h"
#include "MyExceptions.h"
#include <iostream>
#include <cstdlib>
#include <vector>

using namespace std;

int main(int argc, char** argv) {

    ApplicationConstructor appConstructor1("3324","Konstantinos Dimos", "konstantinos@uniwa.gr");
    ApplicationConstructor appConstructor2("3332","Nikos Paulou", "nikos@uniwa.gr");
    ApplicationConstructor appConstructor3("4432","Stavros", "stavros@uniwa.gr");
    Application app1("game1456", "Tetris", "1.0.0", appConstructor1, NULL, 10.0);    
    Application app2("game2245", "Pacman", "1.1.0", appConstructor2, NULL, 15.0);    
    Application app3("game1433", "Doom",  "1.1.1", appConstructor3, NULL, 20.0);
    /*-----------------------------------------------------------------------------------------------------*/
    ApplicationConstructor appConstructor4("2232","Eirini Markou", "eirini@uniwa.gr");
    ApplicationConstructor appConstructor5("1121","Tasos Sotiriou", "tasos@uniwa.gr");
    ApplicationConstructor appConstructor6("4431","Giorgos Papadopoulos", "giorgos@uniwa.gr");
    Application app4("desk4552", "Office", "1.0.0", appConstructor4, NULL, 30.0);    
    Application app5("desk6657", "Photoshop", "1.1.0", appConstructor5, NULL, 25.0);    
    Application app6("desk6643", "Torrent",  "1.1.1", appConstructor6, NULL, 45.0);
    /*-----------------------------------------------------------------------------------------------------*/
    Application appTable[] = {app1, app2, app3, app4, app5, app6};
    vector<Application &> appVector(appTable);   
    AppSystem appSystem(appVector);
}

我得到这个错误：

AppSystem.cpp:12:1：错误：'class std::vector&'中未初始化的引用成员 [-fpermissive]

 AppSystem::AppSystem(向量 &appSystemVector){
 ^~~~~~~~~
在 AppSystem.cpp:8:0 包含的文件中：
AppSystem.h:21:32: 注意: 'std::vector& AppSystem::ApplicationVector' 应该被初始化
         向量 &ApplicationVector;

有什么建议吗？

标签： c++objectvectorconstructor

解决方案

AppSystem::AppSystem(vector<Application &> &appSystemVector){
  ApplicationVector = appSystemVector;
}

这不是您可以初始化作为引用的字段的方式。语法是：

AppSystem::AppSystem(vector<Application &> &appSystemVector) : ApplicationVector(appSystemVector) {
}

这是因为在进入 ctor 的块时，字段已经构建，因此ApplicationVector未初始化，这是不可能的。您正在尝试分配一个与初始化它不同的引用。给出的语法允许您指定字段的初始化方式。

另请注意：

  • 引用向量是不可能的（出于完全相同的原因，只能初始化引用）
  • 使用变量的标准大小写：applicationVector不是ApplicationVector，字段的第一个字母通常是小写。这是约定俗成的问题。

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