C++派生类不能正常工作

Question

我对编程相当陌生，而且我遇到了无法解决的问题。我尝试了所有我能想到的。我准备好这是一个简单的错误。

的main.cpp

#include <iostream> 
#include <iomanip> 
#include "new_employee.h" 
#include "new_employee.cpp" 
#include "permanent_employee.cpp" 

using namespace std; 

int in_employee[4] = {101, 102, 103, 104}; 
int in_bankaccount[4] = {80045001, 80045002, 80045003, 80045004}; 
float in_hours[4] = {40, 50, 50, 51}; 
float in_rate[4] = {22, 22, 24, 26}; 

int main() 
{ 
    for(int i=0;i<4;i++) 
{ 
    new_employee employee[i](in_employee[i], in_bankaccount[i]); 
} 
///permanent_employee employee2(in_employee[1], in_bankaccount[1]); 
///permanent_employee employee3(in_employee[2], in_bankaccount[2]); 
///permanent_employee employee4(in_employee[3], in_bankaccount[3]); 
} 

new_employee.h

#if !defined NEW_EMPLOYEE 
#define NEW_EMPLOYEE 

class new_employee 
{ 
public: 
    new_employee(); 
    new_employee(int employee_number, int account_number); 
private: 
    int employee_no, account_no; 
    float hourly_rate, hours_worked; 
}; 

class permanent_employee : public new_employee 
{ 
public: 
    permanent_employee(); 
    permanent_employee(int employee_number, int account_number); 
private: 
    float union_deduction, vhi_deduction; 
}; 
#endif 

new_employee.cpp

#include <iostream> 
#include <iomanip> 
#include "new_employee.h" 

using namespace std; 

new_employee::new_employee() 
{ 
    employee_no = 0; 
    account_no = 0; 
} 

new_employee::new_employee(int employee_number, int account_number) 
{ 
    employee_no = employee_number; 
    account_no = account_number; 
} 

permanent_employee.cpp

#include <iostream> 
#include <iomanip> 
#include "new_employee.h" 

using namespace std; 

permanent_employee::permanent_employee() 
{ 
    employee_no = 0; 
    account_no = 0; 
} 

permanent_employee::permanent_employee(int employee_number, int account_number) 
{ 
    employee_no = employee_number; 
    account_no = account_number; 
} 

因此，我甚至没有尝试正确运行该程序的原始功能，因为直接从Codeblocks复制了以下错误。

Z:\C++\Assignment 3 - Payroll Processing\new_employee.h||In constructor 'permanent_employee::permanent_employee()':|

Z:\C++\Assignment 3 - Payroll Processing\new_employee.h|10|error: 'int new_employee::employee_no' is private|

Z:\C++\Assignment 3 - Payroll Processing\permanent_employee.cpp|9|error: within this context|

Z:\C++\Assignment 3 - Payroll Processing\new_employee.h|10|error: 'int new_employee::account_no' is private|

Z:\C++\Assignment 3 - Payroll Processing\permanent_employee.cpp|10|error: within this context|

Z:\C++\Assignment 3 - Payroll Processing\new_employee.h||In constructor 'permanent_employee::permanent_employee(int, int)':|

Z:\C++\Assignment 3 - Payroll Processing\new_employee.h|10|error: 'int new_employee::employee_no' is private|

Z:\C++\Assignment 3 - Payroll Processing\permanent_employee.cpp|15|error: within this context|

Z:\C++\Assignment 3 - Payroll Processing\new_employee.h|10|error: 'int new_employee::account_no' is private|

Z:\C++\Assignment 3 - Payroll Processing\permanent_employee.cpp|16|error: within this context|

Z:\C++\Assignment 3 - Payroll Processing\main.cpp||In function 'int main()':|

Z:\C++\Assignment 3 - Payroll Processing\main.cpp|18|error: variable-sized object 'employee' may not be initialized|

Z:\C++\Assignment 3 - Payroll Processing\main.cpp|18|warning: unused variable 'employee' [-Wunused-variable]| ||=== Build finished: 9 errors, 1 warnings (0 minutes, 0 seconds) ===|

我想用派生类permanent_employee做一个基类new_employee。对我来说，看起来每个人都试图访问其他的变量。我会很感激任何反馈。

谢谢你的帮助。

PS。我是新来的这个网站，所以我很抱歉，如果我发布不正确。

Answer 1

您有您的成员变量的可访问性问题。一般可访问是这样的：

公众：任何人，每个人都可以看到和更改这些家伙。 受保护：包含这些变量作为成员和任何派生类的类可以更改这些变量。外部课程无法访问它们。 Private：只有包含这些成员变量的类可以以任何方式修改或使用它们。

该错误是由permanent_employee类试图访问new_employee类的私有成员造成的。您也可以尝试从派生构造函数调用基类构造函数。

你走我非常

无论哪种方式，强烈建议您花一些时间，你做任何事情之前要充分了解公众，保护和私有成员变量和函数之间的差异。这将使你的生活从长远来看变得更容易。

Answer 2

变化：

permanent_employee::permanent_employee(int employee_number, int account_number) 
{ 
    employee_no = employee_number; 
    account_no = account_number; 
} 

调用基类的构造函数：

permanent_employee::permanent_employee(int employee_number, int account_number) 
: new_employee(employee_number, account_number) 
{ 
} 

由于成员变量声明为privatenew_employee，他们不能访问甚至派生类。如果你希望派生类能够修改它们（但有时你不会因为不变的保存），你可以声明它们为protected。