c++ - 类继承 : Constructor and member functions of class not recognized by compiler

Question

我的类继承代码遇到了麻烦:编译器无法识别构造函数。任何成员函数都不是。例如，如果我调用构造函数，我的测试文件(test.cpp)是这样开始的:

#include "salariedemployee.h"//This is a class inherited from 'employee.h', the base class
#include "Administrator.h"//This is a class inherited from "salariedemployee.h"
#include <iostream>
#include <string>
using std::cout;
using std::endl;
using namespace employeessavitch;
int main()
{
    Employee boss("Mr Big Shot","987-65-4321");//I try to call constructor in the base class "employee";
}

编译器报错

undefined reference to `employeessavitch::Employee::Employee(std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::basic_string<char, std::char_traits<char>, std::allocator<char> >)'

如果我尝试调用继承类中的构造函数，例如

SalariedEmployee boss("Mr Big Shot","987-65-4321",10500.50);//a constructor about name, SSN number, and salary

它给出如下错误:

undefined reference to `employeessavitch::SalariedEmployee::SalariedEmployee(std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::basic_string<char, std::char_traits<char>, std::allocator<char> >, double)'

我想知道这是怎么回事？

我的基类头文件写成:

#ifndef EMPLOYEE_H
#define EMPLOYEE_H
#include <string>
using namespace std;
namespace employeessavitch
{
  Employee( );//default constructor
  Employee(string the_name, string the_ssn); constructor about name and ssn
}#endif 

我继承的类头文件是这样写的:

#ifndef SALARIEDEMPLOYEE_H
#define SALARIEDEMPLOYEE_H
#include <string>
#include "employee.h"
using namespace std;
namespace employeessavitch
{
    class SalariedEmployee : public Employee
    {
        public:
           SalariedEmployee( );//default constructor
           SalariedEmployee (string the_name, string the_ssn, double the_weekly_salary);//constructor about name, ssn and salary
           //Other member function and variables are ommitted here.
}#endif

我很确定命名空间没问题，因为我可以编写 std cin 和 cout。

我的 cpp 实现文件是这样的:

#include <string>
#include <cstdlib>
#include <iostream>
#include "employee.h"
using namespace std;
namespace employeessavitch
{
   Employee::Employee( ) : name("No name yet"), ssn("No number yet"), net_pay(0)
   {
     //deliberately empty
   }
 }

和

#include <iostream>
#include <string>
#include "salariedemployee.h"
using namespace std;
namespace employeessavitch
{
    SalariedEmployee::SalariedEmployee( ) : Employee( ), salary(0)
    {
    //deliberately empty
    }
    SalariedEmployee::SalariedEmployee(string the_name, string the_number, double the_weekly_salary): Employee(the_name, the_number), salary(the_weekly_salary)
    {
      //deliberately empty
    }
 }

Answer 1

我相信 Employee 构造函数没有声明为类定义的一部分。

在 employee.h 中试试这个:

namespace employeessavitch
{
  class Employee
  {
    public:
    Employee( );//default constructor
    Employee(string the_name, string the_ssn); //constructor about name and ssn
  };
}