Question

我对C ++很陌生，我正在努力完成一些大学工作。我正在Visual Studio 2010中构建我的C ++程序。我已经倾倒了代码，无法弄清楚它为什么不起作用。以下是我项目中的所有代码。对不起，我必须发布所有内容，但我不知道问题所在。

employee.h

#ifndef EMPLOYEE_H
#define EMPLOYEE_H
#include <string>

using namespace std;

class Employee
{
public:
    int empNumber;

    string getName();
    int getId();
    float getBaseSalary();
    virtual string getTitle();
    virtual int getNumTaskCompleted();
    virtual float getGrossSalary();
    virtual float getBonus();
    virtual void setEmployeeDetails();
};
#endif

employee.cpp

#include <string>
#include <iostream>

using namespace std;

class Employee
{
private:
    string name;
    int id;
    float salary;

public:
    string getName()
    {
        return this->name;
    }

    int getId()
    {
        return this->id;
    }

    float getBaseSalary()
    {
        return this->salary;
    }

    void setEmployeeDetails()
    {
        cout << "Enter employee name (no spaces): ";
        cin >> this->name;
        cout << "Enter employee id (numeric): ";
        cin >> this->id;
        cout << "Enter employee salary: ";
        cin >> this->salary;
    }
};

projectManager.h

#ifndef PROJECT_MANAGER_H
#define PROJECT_MANAGER_H
#include <string>
#include "employee.h"

using namespace std;

class ProjectManager : public Employee
{
public:
    string getTitle();
    int getNumTaskCompleted();
    float getGrossSalary();
    float getBonus();
    void setBonus(float bonus);
    void setEmployeeDetails();
};
#endif

projectManager.cpp

#include <string>
#include <iostream>
#include "employee.h"

using namespace std;

class ProjectManager : public Employee
{
private:
    int numTaskCompleted;
    float bonus;

public:
    string getTitle()
    {
        return "Manager";
    }

    int getNumTaskCompleted()
    {
        return this->numTaskCompleted;
    }

    float getGrossSalary()
    {
        return this->getBaseSalary() + this->bonus;
    }

    float getBonus()
    {
        return this->bonus;
    }

    void setBonus(float bonus)
    {
        this->bonus = bonus;
    }

    void setEmployeeDetails()
    {
        Employee::setEmployeeDetails();

        cout << "Enter tasks completed (numeric): ";
        cin >> this->numTaskCompleted;

        if (numTaskCompleted >= 5)
            this->setBonus(10000.00f);
    }
};

softwareEngineer.h

#ifndef SOFTWARE_ENGINEER_H
#define SOFTWARE_ENGINEER_H
#include <string>
#include "employee.h"

using namespace std;

class SoftwareEngineer : public Employee
{
public:
    string getTitle();
    int getNumTaskCompleted();
    float getGrossSalary();
    float getBonus();
    void setBonus(float bonus);
    void setEmployeeDetails();
};
#endif

softwareEngineer.cpp

#include <string>
#include <iostream>
#include "employee.h"

using namespace std;
class SoftwareEngineer : public Employee
{
private:
    int numTaskCompleted;
    float bonus;

public:
    string getTitle()
    {
        return "Engineer";
    }

    int getNumTaskCompleted()
    {
        return this->numTaskCompleted;
    }

    float getGrossSalary()
    {
        return this->getBaseSalary() + this->bonus;
    }

    float getBonus()
    {
        return this->bonus;
    }

    void setBonus(float bonus)
    {
        this->bonus = bonus;
    }

    void setEmployeeDetails()
    {
        Employee::setEmployeeDetails();

        cout << "Enter tasks completed (numeric): ";
        cin >> this->numTaskCompleted;

        if (numTaskCompleted >= 30)
            this->setBonus(5000.00f);
    }
};

program.cpp

#include <string>
#include <iostream>
#include <iomanip>

#include "employee.h"
#include "projectManager.h"
#include "softwareEngineer.h"

using namespace std;

Employee *_employees[4];

int main()
{
    for (int employeeIndex = 0; employeeIndex < 4; employeeIndex++)
    {
        Employee *CurrentEmployee = new Employee();
        CurrentEmployee->setEmployeeDetails();
        _employees[employeeIndex] = CurrentEmployee;
    }

    cout
        << setw(12) << "Employee" 
        << setw(5) << "Id"
        << setw(15) << "Employee"
        << setw(7) << "Task" 
        << setw(10) << "Base"
        << setw(13) << "Bonus"
        << setw(12) << "Gross" << endl;


    cout
        << setw(11) << "Title" 
        << setw(9) << "Number" 
        << setw(10) << "Name"
        << setw(12) << "Completed"
        << setw(8) << "Salary" 
        << setw(15) << "Entitlement"
        << setw(9) << "Salary" << endl;

    for (int employeeIndex = 0; employeeIndex < 4; employeeIndex++)
    {
        cout
            << setw(12) << _employees[employeeIndex]->getTitle()
            << setw(8)  << _employees[employeeIndex]->getId()
            << setw(13) << _employees[employeeIndex]->getName()  
            << setw(5)  << _employees[employeeIndex]->getNumTaskCompleted()
            << setw(13) << _employees[employeeIndex]->getBaseSalary()
            << setw(14) << _employees[employeeIndex]->getBonus()
            << setw(11) << _employees[employeeIndex]->getGrossSalary() << endl;
    }

    return 0;
}

当我尝试调试此程序时，我收到一条消息，指出存在构建错误。这些是我得到的构建错误。

错误1错误LNK2019：未解析的外部符号“public：int __thiscall Employee :: getId（void）“（？getId @ Employee @@ QAEHXZ）引用在函数_main E：\ C ++中 Assignments \ assignment_7 \ assignment_7 \ program.obj assignment_7 错误3错误LNK2019：未解析的外部符号“public：float __thiscall Employee :: getBaseSalary（void）“ （？getBaseSalary @ Employee @@ QAEMXZ）在函数_main E：\ C ++中引用 Assignments \ assignment_7 \ assignment_7 \ program.obj assignment_7 错误2错误LNK2019：未解析的外部符号“public：class 的std :: basic_string的，类 std :: allocator＆gt; __thiscall Employee :: getName（void）“ （？的getName @ @@雇员QAE？AV？$ basic_string的@ DU？$ char_traits @ d @ @@ STD V'$分配器@ d @ @@ 2 STD @@ XZ）在函数_main E：\ C ++中引用 Assignments \ assignment_7 \ assignment_7 \ program.obj assignment_7 错误8错误LNK2001：未解析的外部符号“public：virtual void __thiscall Employee :: setEmployeeDetails（void）“ （？setEmployeeDetails @ Employee @@ UAEXXZ）E：\ C ++ Assignments \ assignment_7 \ assignment_7 \ program.obj assignment_7 错误5错误LNK2001：未解析的外部符号“public：virtual int __thiscall Employee :: getNumTaskCompleted（void）“ （？getNumTaskCompleted @ Employee @@ UAEHXZ）E：\ C ++ Assignments \ assignment_7 \ assignment_7 \ program.obj assignment_7 错误6错误LNK2001：未解析的外部符号“public：virtual float __thiscall Employee :: getGrossSalary（void）“ （？getGrossSalary @ Employee @@ UAEMXZ）E：\ C ++ Assignments \ assignment_7 \ assignment_7 \ program.obj assignment_7 错误7错误LNK2001：未解析的外部符号“public：virtual float __thiscall Employee :: getBonus（void）“ （？getBonus @ Employee @@ UAEMXZ）E：\ C ++

我完全不知道这些错误是什么意思。我已查找错误代码，但无法从他们那里获得任何可以帮助我理解我做错的信息。

任何人都可以找出问题所在吗？谢谢！

Answer 1

这些是链接器错误...在编译器完成将C ++代码编译成目标文件之后，链接器然后将这些文件“链接”到一个可执行文件中。链接器虽然说它无法找到在main函数中调用的链接在一起的函数。

我现在看到的一个大问题是，你已经在头文件中声明了你的类，但是你在你的.cpp文件中重新声明了它们。这会引起问题。 在您的标题文件中声明您的类（就像您已经完成的那样），但定义您的.cpp文件中的类函数（您正在重新执行您的声明） .cpp文件以及定义）。

Answer 2

class Employee和employee.h中有employee.cpp的多个定义。在employee.h中声明类Employee并在employee.cpp中定义其方法

Answer 3

正如其他人所说，你在不同的文件中多次声明了相同的类。根据经验，对类定义使用头文件（.h扩展名），对定义使用源文件（.cpp扩展名）。将它们放在两个地方都是不必要的和错误的。

Answer 4

您不需要在头文件和源文件中包含类声明。实施应如下所示：

employee.cpp

#include <string>
#include <iostream>

using namespace std;

string Employee::getName()
{
    return this->name;
}

Answer 5

从头到尾......试试这个：

employee.h：

#ifndef EMPLOYEE_H
#define EMPLOYEE_H

#include <string>

class Employee
{
private:
    std::string name;
    int id;
    float salary;

public:
    int empNumber;

    std::string getName();

    // Etc...

};
#endif

employee.cpp：

#include "employee.h"

std::string Employee::getName()
{
    return name;
}

// Etc...

顺便说一下，在标题中避免使用using namespace - 这会“无意中”污染大量代码。只在CPPs中这样做。

C ++新手 - 标头重新定义错误，链接错误

5 个答案: