Question

我有基类Manager和派生类Worker，继承似乎正常工作 - 我已经使用它创建了派生类的新对象的默认值构造函数，我可以正确输出。但现在我想为派生类（Worker）创建一个重载的构造函数，似乎有编译错误，我厌倦了寻找答案，但我没有找到答案。为什么编译说Worker没有id，姓名和薪水字段？我已经通过这本书创建了一个派生类，并为它创建了ctors。

Manager标题：

#include <string>
#ifndef MANAGER_H
#define MANAGER_H

class Manager
{
public:
    Manager (); //ctor
    Manager (std::string, std::string, float, int); //overloaded ctor
    friend void display (Manager&); //friend function is declared
    ~Manager (); //dtor
protected:
    std::string id;
    std::string name;
    float salary;
private:
    int clearance;
};

Manager cpp：

#include <iostream>
#include "Manager.h"
#include "Worker.h"

Manager::Manager() //default ctor
{
id = "M000000";
name = "blank";
salary = 0;
clearance = 0;
}

Manager::Manager(std::string t_id, std::string t_name, float wage, int num): id (t_id), name      (t_name), salary(wage), clearance (num)
{
//overloaded ctor
}

Manager::~Manager()
{
 //dtor
}

Worker标题：

#include <string>
#ifndef Worker_H
#define Worker_H

class Worker: public Manager
{
public:
    Worker();
    Worker (std::string, std::string, float, int);
    ~Worker();
     friend void display (Worker&); //friend function is declared
protected:
    int projects;
private:

};

#endif // Worker_H

Worker cpp：

#include <iostream>
#include "Manager.h"
#include "Worker.h"

Worker::Worker() //default ctor
{
id = "w000000";
name = " - ";
salary = 0;
projects = 0;

}
Worker::Worker(std::string t_id, std::string t_name, float wage, int num) : id (t_id), name (t_name), salary (wage), projects (num);
{
//ctor
}
Worker::~Worker()
{
//dtor
}

Answer 1

 Worker::Worker(std::string t_id, std::string t_name, float wage, int num) : id (t_id), name (t_name), salary (wage), projects (num)
{
//ctor
}

这里初始化基类中定义的成员ID，名称，工资和许可。您需要将它传递给基类构造函数进行初始化。你不能直接初始化它们 id，name和clearance受到保护，因此您可以在派生类中访问它们，但不能使用初始化列表直接初始化它们。您可以initialize inside the constructor或make a call to base constructor in initialization list。

Worker::Worker(std::string t_id, std::string t_name, float wage, int num):Manager(t_id,t_name,wage,0), projects (num)
{
//ctor
}

Answer 2

派生类不会看到其基类的私有成员。你必须委托构造函数。

Answer 3

您的Worker构造函数应该是：

Worker::Worker() : Manager("w000000", " - ", 0, 0) {}

Worker::Worker(std::string t_id, std::string t_name, float wage, int num) :
     Manager(t_id, t_name, wage, num)
{
}

派生类中的重载构造函数

3 个答案: