编写一个普通的发放工资的函数，函数要求采用多态语句实现工资的发放。编写一个主程序，创建四个类对象，及四个不同类型员工，调用发放工资的普通函数，计算并显示四个人的工资。采用多文件结构实现程序

好的，以下是实现该要求的代码：

首先是 Employee.h 文件，定义了一个基类 Employee：

#ifndef EMPLOYEE_H
#define EMPLOYEE_H

#include <string>

class Employee {
public:
    Employee(std::string name);
    virtual ~Employee();
    virtual double calculate_salary() = 0;

protected:
    std::string m_name;
};

#endif

然后是 SalariedEmployee.h 文件，继承自 Employee 类，实现了 calculate_salary 函数：

#ifndef SALARIEDEMPLOYEE_H
#define SALARIEDEMPLOYEE_H

#include "Employee.h"

class SalariedEmployee : public Employee {
public:
    SalariedEmployee(std::string name, double base_salary);
    virtual ~SalariedEmployee();
    virtual double calculate_salary();

private:
    double m_base_salary;
};

#endif

接着是 HourlyEmployee.h 文件，同样继承自 Employee 类，实现了 calculate_salary 函数：

#ifndef HOURLYEMPLOYEE_H
#define HOURLYEMPLOYEE_H

#include "Employee.h"

class HourlyEmployee : public Employee {
public:
    HourlyEmployee(std::string name, double hourly_rate, double hours_worked);
    virtual ~HourlyEmployee();
    virtual double calculate_salary();

private:
    double m_hourly_rate;
    double m_hours_worked;
};

#endif

然后是 CommissionEmployee.h 文件，同样继承自 Employee 类，实现了 calculate_salary 函数：

#ifndef COMMISSIONEMPLOYEE_H
#define COMMISSIONEMPLOYEE_H

#include "Employee.h"

class CommissionEmployee : public Employee {
public:
    CommissionEmployee(std::string name, double commission_rate, double sales);
    virtual ~CommissionEmployee();
    virtual double calculate_salary();

private:
    double m_commission_rate;
    double m_sales;
};

#endif

最后是 Payroll.cpp 文件，实现了发放工资的普通函数，以及主程序：

#include <iostream>
#include "Employee.h"
#include "SalariedEmployee.h"
#include "HourlyEmployee.h"
#include "CommissionEmployee.h"

double calculate_payroll(Employee* employee) {
    return employee->calculate_salary();
}

int main() {
    SalariedEmployee salaried_employee("John Smith", 4000);
    HourlyEmployee hourly_employee("Jane Doe", 20, 40);
    CommissionEmployee commission_employee("Bob Johnson", 0.1, 5000);
    Employee* employee = new Employee("Mary Brown");

    std::cout << "Salaried employee " << salaried_employee.calculate_salary() << std::endl;
    std::cout << "Hourly employee " << hourly_employee.calculate_salary() << std::endl;
    std::cout << "Commission employee " << commission_employee.calculate_salary() << std::endl;
    std::cout << "Employee " << employee->calculate_salary() << std::endl;

    delete employee;
    employee = nullptr;

    return 0;
}

以上代码实现了要求的功能，即创建了四个不同类型的员工对象，并调用发放工资的普通函数，计算并显示四个人的工资。