C ++:将对象添加到集合中 [英] C++ : adding an object to a set

问题描述

我在将对象添加到集合时遇到麻烦.

I am having trouble with adding an object to a set.

我在头文件中使用两个类，一个用于雇员，第二个用于经理.在经理类中，我想通过添加作为特定经理下属的员工来创建一组员工.首先，我创建一个空集，可以通过调用一个函数为其添加对象.

I use two classes in a header file, one for employees and a second one for managers. In the manager class I want to create a set of employees by adding employees who are subordinates for a particular manager. First I create a empty set for which I can add objects by calling a function.

它看起来如下:

头文件

#ifndef EMPLOYEE_HH
#define EMPLOYEE_HH

#include <set>
#include <string>
#include <iostream>

using namespace std ;

class Employee {
    public:
      // Constructor
      Employee(const char* name, double salary) :
         _name(name),
         _salary(salary) {
      }

      // Accessors
      const char* name() const { 
         return _name.c_str() ;
      }
      double salary() const {
         return _salary ;
      }

    private:
      string _name ;
      double _salary ;

} ;

class Manager : public Employee {
    public:
      //Constructor
      Manager(const char* _name, double _salary):
         Employee(_name, _salary),
         _subordinates() {
      }

      // Accessors/Modifiers
      void addSubordinate(Employee& empl) {
         _subordinates.insert(empl) ;     // Error: no macthing function call for .insert()    
      }

    private:
      set<Employee*> _subordinates ;        

} ;

#endif  

主脚本

#include <string>
#include <iostream>
#include "Employee.hh"

using namespace std ;

int main() {

    Employee emp = ("David", 10000) ;

    Manager mgr = ("Oscar", 20000) ;

    mgr.addSubordinate(emp);    

    return 0;

}

编译时出现错误，提示_subordinates.insert(empl)无法调用任何匹配函数.

When compiling I get the error that no matching function can be called for _subordinates.insert(empl).

推荐答案

元素set的类型为Employee*，但是您要插入Employee.

The element's type of set is Employee*, but you're inserting Employee.

您可以将_subordinates.insert(empl);更改为_subordinates.insert(&empl);.

(将_subordinates的类型从set<Employee*>更改为set<Employee>也可以修复编译器错误，但似乎与请求不匹配.)

(Changing the type of _subordinates from set<Employee*> to set<Employee> could fix the compiler error too, but it seems doesn't match the request.)

请注意，如@KenmanTsang所指出的那样，使用从堆栈变量获取的指针可能很危险.考虑将智能指针与new一起使用，例如std::set<std::unique_ptr<Employee>> _subordinates;.

Note as @KenmanTsang pointed, using pointer got from stack variable might be dangerous. Consider about using smart pointer with new, such as std::set<std::unique_ptr<Employee>> _subordinates;.

顺便说一句:

Employee emp = ("David", 10000) ;
Manager mgr = ("Oscar", 20000) ;

应该是

Employee emp ("David", 10000) ;
Manager mgr ("Oscar", 20000) ;

或(自c ++ 11起)

or (since c++11)

Employee emp = {"David", 10000} ;
Manager mgr = {"Oscar", 20000} ;

这篇关于C ++:将对象添加到集合中的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！