c++ - C++“错误LNK2019:无法解析的外部符号”(多个实例)

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我猜这个网站上的某人似乎认为这是在其他地方回答的。无论如何，我自己弄清楚了，我所要做的就是在解决方案资源管理器的“源文件”部分中包含“ EmployeeRecord.cpp”文件。现在，我遇到了另一个问题，因此我将回答这个问题，并问其他地方。

头文件：

/*******************************************************************
*   File: EmployeeRecord.h
*   Name: You don't need this
*   Assignment 1: Employee Record
*
*   This program is entirely my own work
*******************************************************************/

// ------------------------------------------------
// EmployeeRecord.h
// Purpose: defining the EmployeeRecord class
// ------------------------------------------------

#ifndef EMPLOYEERECORD_H
#define EMPLOYEERECORD_H

#include <iostream>
#include <string>
using namespace std;

class EmployeeRecord
{
private:
    // private variables
    int m_iEmployeeID;     // employee ID
    char m_sLastName[32];  // employee last name
    char m_sFirstName[32]; // employee first name
    int m_iDeptID;         // department ID
    double m_dSalary;      // employee salary

public:
    // define constructors
    EmployeeRecord();
    EmployeeRecord(int ID, char *fName, char *lName, int dept, double sal);

    // destructor
    ~EmployeeRecord();

    // accessor, mutator, and data manipulation funcitons
    int getID();
    void setID(int ID);

    void getName(char *fName, char *lName);
    void setName(char *fName, char *lName);

    void getDept(int& d);
    void setDept(int d);

    void getSalary(double *sal);
    void setSalary(double sal);
    void printRecord();
};

#endif

对象文件（最重要）：

/*******************************************************************
*   File: EmployeeRecord.cpp
*   Name: You don't need this
*   Assignment 1: Employee Record
*
*   This program is entirely my own work
*******************************************************************/

// ------------------------------------------------
// EmployeeRecord.cpp
// Purpose: implementing the funcitons of the EmployeeRecord class
// ------------------------------------------------

#include "EmployeeRecord.h"

//constructor 1 (default)
EmployeeRecord::EmployeeRecord()
{
    m_iEmployeeID = 0;
    m_sLastName = "";
    m_sFirstName = "";
    m_iDeptID = 0;
    m_dSalary = 0.0;
}

// this constructor shall set the member variables to the values passed into the function
EmployeeRecord::EmployeeRecord(int ID, char *fName, char *lName, int dept, double sal)
{
    m_iEmployeeID = ID;
    m_sFirstName = *fName;
    m_sLastName = *lName;
    m_iDeptID = dept;
    m_dSalary = sal;
}

// destructor - cleans up and deallocates any memory that pointers within this class may have referenced to
EmployeeRecord::~EmployeeRecord(){};

// function getID shall return the int value stored in the member variable m_iEmployeeID
int EmployeeRecord::getID()
{
    return m_iEmployeeID;
}

// function setID will set the member variable m_iEmployeeID to the value of its' argument
void EmployeeRecord::setID(int ID)
{
    m_iEmployeeID = ID;
}

// the getName() function shall copy the member variables m_sFirstName and m_sLastName into the character
// arrays pointed to by the function arguments
void EmployeeRecord::getName(char *fName, char *lName)
{
    *fName = m_sFirstName;
    *lName = m_sLastName;
}

// the setName() function will copy the function arguments into the member variables m_sFirstName and m_sLastName
void EmployeeRecord::setName(char *fName, char *lName)
{
    m_sFirstName = *fName;
    m_sLastName = *lName;
}

// the getDept() function shall be defined as a reference function. That is, a call to this function will copy the
// member variable m_iDeptID into the int variable referenced by the function argument
void EmployeeRecord::getDept(int& d)
{
    d = m_iDeptID;
}

// the setDept() function will copy the function argument into the member variable m_iDeptID
void EmployeeRecord::setDept(int d)
{
    m_iDeptID = d;
}

// the getSalary() function shall be defined as a pointer function. That is, a call to this function will copy the
// member variable m_dSalary into the int variable pointed to by the function argument
void EmployeeRecord::getSalary(double *sal)
{
    *sal = m_dSalary;
}

// the function setSalary() shall copy the function argument into the member variable m_dSalary
void EmployeeRecord::setSalary(double sal)
{
    m_dSalary = sal;
}

// this function shall print to the screen all data found in the employee's record
void EmployeeRecord::printRecord()
{
    cout << "Employee ID:   " << m_iEmployeeID << endl;
    cout << "Last Name:     " << m_sLastName << endl;
    cout << "First Name:    " << m_sFirstName << endl;
    cout << "Department ID: " << m_iDeptID << endl;
    cout << "Salary:        " << m_dSalary << endl;
}

主文件：

/*******************************************************************
*   main function for project Prog1
*******************************************************************/

#include <stdio.h>
#include <time.h>
#include <cstdlib>
#include <windows.h>

#include <string>
#include <iostream>
using namespace std;

#include "EmployeeRecord.h"

int main(void)
{

    int answer, employee_id, dept_id, i;
    char  firstname[35], lastname[35];
    double *salary;

    menu:
    do
    {
        cout << "This program is used to create and modify employee records. This program was" << endl;
        cout << "created and tested by John Doe exclusively under the guidance of the" << endl;
        cout << "Random School Name Here." << endl << endl;
        cout << "Any attempt to copy this program and falsify its origins is punishable under" << endl;
        cout << "both state and federal law." << endl << endl;
        cout << "Thank you for using this program, and I hope you enjoy it." << endl << endl;
        system("pause");

        system("CLS");
        cout << "--------------------------------------------------------------------------------" << endl;
        cout << "                               EMPLOYEE RECORD" << endl;
        cout << "                 Creating and Modifying an Employee Record" << endl << endl;
        cout << "--------------------------------------------------------------------------------" << endl;
        cout << "                            What would you like to do?" << endl << endl;
        cout << " 1. Create a new Employee Record" << endl << endl;
        cout << " 2. Obtain the Employee ID of the current Employee Record" << endl << endl;
        cout << " 3. Enter the Employee ID into the current Employee Record" << endl << endl;
        cout << " 4. Enter the Employee's Name into the current Employee Record" << endl << endl;
        cout << " 5. Enter the Department ID into the current Employee Record" << endl << endl;
        cout << " 6. Enter the Employee's Annual Salary into the current Employee Record" << endl << endl;
        cout << " 7. Print the current Employee Record" << endl << endl;
        cout << " 8. Quit" << endl << endl;
        cin >> answer;


        if (answer == 1)
        {
            system("CLS");
            cout << "--------------------------------------------------------------------------------" << endl;
            cout << "                               EMPLOYEE RECORD" << endl;
            cout << "                 Creating and Modifying an Employee Record" << endl << endl;
            cout << "--------------------------------------------------------------------------------" << endl;
            cout << "                            What would you like to do?" << endl << endl;
            cout << " 1. Create a new Employee Record" << endl << endl;
            cout << "           Enter the Employee's ID:             ";
            cin >> employee_id;
            cout << endl;
            cout << "           Enter the Employee's First Name:     ";
            i = 0;
            cin >> firstname[i];
            while (firstname[i] != '\n' && i < 35)
            {
                i++;
                cin >> firstname[i];
            }
            cout << endl;
            cout << "           Enter the Employee's Last Name:      ";
            i = 0;
            cin >> lastname[i];
            while (lastname[i] != '\n' && i < 35)
            {
                i++;
                cin >> lastname[i];
            }
            cout << endl;
            cout << "           Enter the Department Number:         ";
            cin >> dept_id;
            cout << endl;
            cout << "           Enter the Employee's Annual Salary: $";
            cin >> *salary;

            //EmployeeRecord Employee1 = EmployeeRecord();
            EmployeeRecord Employee1 = EmployeeRecord(employee_id, firstname, lastname, dept_id, *salary);
            Employee1.printRecord();
            system("pause");
            system("CLS");
            goto menu;
        }


        else if (answer == 2)
        {
            EmployeeRecord Employee1 = EmployeeRecord(employee_id, firstname, lastname, dept_id, *salary);
            system("CLS");
            cout << "--------------------------------------------------------------------------------" << endl;
            cout << "                               EMPLOYEE RECORD" << endl;
            cout << "                 Creating and Modifying an Employee Record" << endl << endl;
            cout << "--------------------------------------------------------------------------------" << endl;
            cout << "                            What would you like to do?" << endl << endl;
            cout << " 1. Create a new Employee Record" << endl << endl;
            cout << " 2. Obtain the Employee ID of the current Employee Record" << endl << endl;
            cout << "           The current Employee ID is: " << Employee1.getID();
            system("pause");
            system("CLS");
            goto menu;
        }


        else if (answer == 3)
        {
            EmployeeRecord Employee1 = EmployeeRecord(employee_id, firstname, lastname, dept_id, *salary);
            system("CLS");
            cout << "--------------------------------------------------------------------------------" << endl;
            cout << "                               EMPLOYEE RECORD" << endl;
            cout << "                 Creating and Modifying an Employee Record" << endl << endl;
            cout << "--------------------------------------------------------------------------------" << endl;
            cout << "                            What would you like to do?" << endl << endl;
            cout << " 1. Create a new Employee Record" << endl << endl;
            cout << " 2. Obtain the Employee ID of the current Employee Record" << endl << endl;
            cout << " 3. Enter the Employee ID into the current Employee Record" << endl << endl;
            cout << "          Enter the Employee ID: ";
            cin >> employee_id;
            Employee1.setID(employee_id);
            Employee1.printRecord();
            system("pause");
            system("CLS");
            goto menu;
        }


        else if (answer == 4)
        {
            EmployeeRecord Employee1 = EmployeeRecord(employee_id, firstname, lastname, dept_id, *salary);
            system("CLS");
            cout << "--------------------------------------------------------------------------------" << endl;
            cout << "                               EMPLOYEE RECORD" << endl;
            cout << "                 Creating and Modifying an Employee Record" << endl << endl;
            cout << "--------------------------------------------------------------------------------" << endl;
            cout << "                            What would you like to do?" << endl << endl;
            cout << " 1. Create a new Employee Record" << endl << endl;
            cout << " 2. Obtain the Employee ID of the current Employee Record" << endl << endl;
            cout << " 3. Enter the Employee ID into the current Employee Record" << endl << endl;
            cout << " 4. Enter the Employee's Name into the current Employee Record" << endl << endl;
            Employee1.getName(firstname, lastname);
            cout << "          Enter the Employee's First Name: ";
            cin >> firstname;
            cout << "                            and Last Name: ";
            cin >> lastname;
            Employee1.setName(firstname, lastname);
            Employee1.printRecord();
            system("pause");
            system("CLS");
            goto menu;
        }


        else if (answer == 5)
        {
            EmployeeRecord Employee1 = EmployeeRecord(employee_id, firstname, lastname, dept_id, *salary);
            system("CLS");
            cout << "--------------------------------------------------------------------------------" << endl;
            cout << "                               EMPLOYEE RECORD" << endl;
            cout << "                 Creating and Modifying an Employee Record" << endl << endl;
            cout << "--------------------------------------------------------------------------------" << endl;
            cout << "                            What would you like to do?" << endl << endl;
            cout << " 1. Create a new Employee Record" << endl << endl;
            cout << " 2. Obtain the Employee ID of the current Employee Record" << endl << endl;
            cout << " 3. Enter the Employee ID into the current Employee Record" << endl << endl;
            cout << " 4. Enter the Employee's Name into the current Employee Record" << endl << endl;
            cout << " 5. Enter the Department ID into the current Employee Record" << endl << endl;
            Employee1.getDept(dept_id);
            cout << "          Enter the Department ID: ";
            cin >> dept_id;
            Employee1.setDept(dept_id);
            Employee1.printRecord();
            system("pause");
            system("CLS");
            goto menu;
        }


        else if (answer == 6)
        {
            EmployeeRecord Employee1 = EmployeeRecord(employee_id, firstname, lastname, dept_id, *salary);
            system("CLS");
            cout << "--------------------------------------------------------------------------------" << endl;
            cout << "                               EMPLOYEE RECORD" << endl;
            cout << "                 Creating and Modifying an Employee Record" << endl << endl;
            cout << "--------------------------------------------------------------------------------" << endl;
            cout << "                            What would you like to do?" << endl << endl;
            cout << " 1. Create a new Employee Record" << endl << endl;
            cout << " 2. Obtain the Employee ID of the current Employee Record" << endl << endl;
            cout << " 3. Enter the Employee ID into the current Employee Record" << endl << endl;
            cout << " 4. Enter the Employee's Name into the current Employee Record" << endl << endl;
            cout << " 5. Enter the Department ID into the current Employee Record" << endl << endl;
            cout << " 6. Enter the Employee's Annual Salary into the current Employee Record" << endl << endl;
            Employee1.getSalary(salary);
            cout << "          Enter the Employee's Annual Salary: ";
            cin >> *salary;
            Employee1.setSalary(*salary);
            Employee1.printRecord();
            system("pause");
            system("CLS");
            goto menu;
        }


        else if (answer == 7)
        {
            EmployeeRecord Employee1 = EmployeeRecord(employee_id, firstname, lastname, dept_id, *salary);
            system("CLS");
            cout << "--------------------------------------------------------------------------------" << endl;
            cout << "                               EMPLOYEE RECORD" << endl;
            cout << "                 Creating and Modifying an Employee Record" << endl << endl;
            cout << "--------------------------------------------------------------------------------" << endl;
            cout << "                            What would you like to do?" << endl << endl;
            cout << " 1. Create a new Employee Record" << endl << endl;
            cout << " 2. Obtain the Employee ID of the current Employee Record" << endl << endl;
            cout << " 3. Enter the Employee ID into the current Employee Record" << endl << endl;
            cout << " 4. Enter the Employee's Name into the current Employee Record" << endl << endl;
            cout << " 5. Enter the Department ID into the current Employee Record" << endl << endl;
            cout << " 6. Enter the Employee's Annual Salary into the current Employee Record" << endl << endl;
            cout << " 7. Print the current Employee Record" << endl << endl;
            Employee1.printRecord();
            system("pause");
            system("CLS");
            goto menu;
        }
    } while (answer == 1 || answer == 2 || answer == 3 || answer == 4 || answer == 5 || answer == 6 || answer == 7);

    if (answer != 8)
    {
        system("CLS");
        cout << "Invalid input! Please Choose one of the 8 options below, then press [Enter]." << endl << endl;
        cout << "--------------------------------------------------------------------------------" << endl;
        cout << "                               EMPLOYEE RECORD" << endl;
        cout << "                 Creating and Modifying an Employee Record" << endl << endl;
        cout << "--------------------------------------------------------------------------------" << endl;
        cout << "                            What would you like to do?" << endl << endl;
        cout << " 1. Create a new Employee Record" << endl << endl;
        cout << " 2. Obtain the Employee ID of the current Employee Record" << endl << endl;
        cout << " 3. Enter the Employee ID into the current Employee Record" << endl << endl;
        cout << " 4. Enter the Employee's Name into the current Employee Record" << endl << endl;
        cout << " 5. Enter the Department ID into the current Employee Record" << endl << endl;
        cout << " 6. Enter the Employee's Annual Salary into the current Employee Record" << endl << endl;
        cout << " 7. Print the current Employee Record" << endl << endl;
        cout << " 8. Quit" << endl << endl;
        cin >> answer;
    }

    else if (answer == 8)
    {
        system("CLS");
        cout << endl << endl << endl << endl << "                 THANKS FOR USING THE EMPLOYEE RECORD PROGRAM" << endl << endl;
        cout << "Closing program in... 5 s";
        Sleep(1000);

        system("CLS");
        cout << endl << endl << endl << endl << "                 THANKS FOR USING THE EMPLOYEE RECORD PROGRAM" << endl << endl;
        cout << "Closing program in... 4 s";
        Sleep(1000);

        system("CLS");
        cout << endl << endl << endl << endl << "                 THANKS FOR USING THE EMPLOYEE RECORD PROGRAM" << endl << endl;
        cout << "Closing program in... 3 s";
        Sleep(1000);

        system("CLS");
        cout << endl << endl << endl << endl << "                 THANKS FOR USING THE EMPLOYEE RECORD PROGRAM" << endl << endl;
        cout << "Closing program in... 2 s";
        Sleep(1000);

        system("CLS");
        cout << endl << endl << endl << endl << "                 THANKS FOR USING THE EMPLOYEE RECORD PROGRAM" << endl << endl;
        cout << "Closing program in... 1 s";
        Sleep(1000);

        system("CLS");
        cout << endl << endl << endl << endl << "                                    GOODBYE!" << endl << endl;
        Sleep(1000);
    }
}

因此，基本上，我有这三个文件，在第三个文件（主文件）中使用了两个文件（对象和标头），以测试功能是否按目标文件中的注释代码所述完成了工作。我还不能发布图像，因此这是向您展示我的解决方案资源管理器的最佳尝试：

Solution 'CS 221' (1 project)
 Solution Items
  EmployeeRecord.cpp
 **CS 221**
  External Dependencies
  Header Files
   EmployeeRecord.h
  Resource Files
  Source Files
   EmployeeRecord_main.cpp

重要的是要知道我不必上交主文件，只需上交对象和标头...我对面向对象的编程非常陌生，所以我认为我的错误只是技术性错误，而不是真正的错误。代码...但也可能是我包含了析构函数的事实...

无论如何，请帮助我使用非常笨拙的措辞解决错误，因为正如我在上一段中所述，这是我第一次尝试面向对象的编程。

编辑：

你们中的许多人都要求我将其他源代码（我一直在称为目标文件）包含在“解决方案项目”中，然后给出确切的错误消息，因此它们是：

错误1错误LNK2019：无法解析的外部符号“公共：__thiscall EmployeeRecord :: EmployeeRecord（int，char *，char *，int，double）”（?? 0EmployeeRecord @@ QAE @ HPAD0HN @ Z）在函数_main C：\ Users中引用\ Tom \ Desktop \ CS 221 \ EmployeeRecord_main.obj

错误2错误LNK2019：未解析的外部符号“公共：__thiscall EmployeeRecord ::〜EmployeeRecord（void）”（?? 1EmployeeRecord @@ QAE @ XZ）在函数_main C：\ Users \ Tom \ Desktop \ CS 221 \ EmployeeRecord_main.obj中引用

错误3错误LNK2019：未解析的外部符号“公共：int __thiscall EmployeeRecord :: getID（void）”（？getID @ EmployeeRecord @@ QAEHXZ）在函数_main C：\ Users \ Tom \ Desktop \ CS 221 \ EmployeeRecord_main.obj中引用

错误4错误LNK2019：未解析的外部符号“公共：void __thiscall EmployeeRecord :: setID（int）”（？setID @ EmployeeRecord @@ QAEXH @ Z）在函数_main C：\ Users \ Tom \ Desktop \ CS 221 \ EmployeeRecord_main中引用。对象

错误5错误LNK2019：未解析的外部符号“公共：void __thiscall EmployeeRecord :: getName（char *，char *）”（？getName @ EmployeeRecord @@ QAEXPAD0 @ Z）在函数_main C：\ Users \ Tom \ Desktop \ CS中引用221 \ EmployeeRecord_main.obj

错误6错误LNK2019：未解析的外部符号“ public：void __thiscall EmployeeRecord :: setName（char *，char *）”（？setName @ EmployeeRecord @@ QAEXPAD0 @ Z）在函数_main C：\ Users \ Tom \ Desktop \ CS中引用221 \ EmployeeRecord_main.obj

错误7错误LNK2019：未解析的外部符号“公共：void __thiscall EmployeeRecord :: getDept（int＆）”（？getDept @ EmployeeRecord @@ QAEXAAH @ Z）在函数_main C：\ Users \ Tom \ Desktop \ CS 221 \ EmployeeRecord_main中引用.obj

错误8错误LNK2019：未解析的外部符号“公共：void __thiscall EmployeeRecord :: setDept（int）”（？setDept @ EmployeeRecord @@ QAEXH @ Z）在函数_main C：\ Users \ Tom \ Desktop \ CS 221 \ EmployeeRecord_main中引用。对象

错误9错误LNK2019：未解析的外部符号“ public：void __thiscall EmployeeRecord :: getSalary（double *）”（？getSalary @ EmployeeRecord @@ QAEXPAN @ Z）在函数_main C：\ Users \ Tom \ Desktop \ CS 221 \ EmployeeRecord_main中引用.obj

错误10错误LNK2019：未解析的外部符号“ public：void __thiscall EmployeeRecord :: setSalary（double）”（？setSalary @ EmployeeRecord @@ QAEXN @ Z）在函数_main C：\ Users \ Tom \ Desktop \ CS 221 \ EmployeeRecord_main中引用。对象

错误11错误LNK2019：未解析的外部符号“公共：void __thiscall EmployeeRecord :: printRecord（void）”（？printRecord @ EmployeeRecord @@ QAEXXZ）在函数_main C：\ Users \ Tom \ Desktop \ CS 221 \ EmployeeRecord_main.obj中引用

错误12错误LNK1120：11无法解析的外部C：\ Users \ Tom \ Desktop \ CS 221 \ Debug \ CS 221.exe

最佳答案

每当在.h文件中声明析构函数（或通常的任何方法）时，都必须在某处定义它。所以：

// a.h
class A {
   A();
   ~A();
}

和：

// a.cpp
A::A() {
   // Do Init Stuff here.
}

A::~A() {
   // Do Destructor Stuff here.
}

您的编译器可以并且将为您创建一个默认构造函数（how much does the default destructor do，请参见此处，了解它可以为您做些什么）以及一个copyconstructor和一个默认构造函数。如果您自行声明它们或将其声明为其他非默认析构函数，则不会这样做。

简而言之：
如果在.h文件中放入析构函数声明，则必须在.cpp文件中定义它！

否则，编译器将读取您的声明，并认为“哦，必须在某些cpp文件中声明它，我以后再链接它”，然后将找不到它。如果您的班级中没有任何成员属于Pointer，则不需要自定义析构函数（除非您想要任何副作用）。因此，您可以使用默认的析构函数。