C ++修复链接器[错误]

Question

我仍在学习如何在头文件中使用类，并且遇到了问题。 无论出于什么原因，我在运行程序时都会收到错误“ V3_Employee.cpp :(。text + 0x3e）：对`Employee :: print（std :: string）'的未定义引用”。

我相信这与编译器与.o文件或此类文件的交互有关。

main.cpp

#include <iostream>
#include <string>
#include "V3_Employee.h"    //Including header file of for class Burrito

using namespace std;

int main()
{

    Employee Sean("Sean");

    return(0);

}

员工

//Header guard
#ifndef V3_EMPLOYEE_H   //If this header has not already been included in main.cpp
#define V3_EMPLOYEE_H   //Then include the following lines of code

#include <string>

using namespace std;

class Employee  //Creating a class named 'Employee'
    {
        private:

            //Creating variables
            string m_name;

        //Creating a public interface
        public:

            //Creating a Construct
            Employee(string m_name);

            //Creating a 'Member function', another name for a function inside a class              
            void print(string m_name);
    };

endif //代码结尾

员工档案

#include "V3_Employee.h"
#include <iostream>
#include <string>

using namespace std;

Employee::Employee(string m_name)
    {
        print(name);
    }

void print(string name) //Defining the function 'print'
    {
        cout<<"Name: "<<m_name<<endl; 
    }

我还有另一个几乎完全相同的代码，而不是使用整数输入而不是字符串：

main2.cpp

#include <iostream>
#include "V2_Burrito.h" //Including header file of for class Burrito

using namespace std;

int main()
{

    Burrito Test(1);    //Setting 'Test' as an object of class 'Burrito' with an input of '1'

    return(0);

}

墨西哥卷饼

//Header guard
#ifndef V2_BURRITO_H    //If this header has not already been included in main.cpp
#define V2_BURRITO_H    //Then include the following lines of code

class Burrito   //Creating a class named 'Burrito'
    {
        //Creating a public interface
        public:
            //Creating a 'Constructor', or a way to manipulate 'private' data
            Burrito(int a); //This constructor contains 1 input in the form of an integer

            //Creating a 'Member function', another name for a function inside a class
            void setType(int a);
    };

#endif  //End of code

感谢您提供的任何帮助！

Answer 1

在类Employee未定义void print(string name) ，因此您的链接器抱怨找不到它。

您应该将代码更改为：

void Employee::print(string name) {
   ...
}

然后定义它，链接器将找到此函数。

顺便说一句，由于只打印字符串，因此最好传递const referense ，因此最好像下面这样编写：

void Employee::print(const string& name) {
   ...
}

但这也不好，因为print函数是Employee的成员函数，它知道要打印哪个变量，因此最好将代码更改为：

void Employee::print() {
   cout<<"Name: "<<m_name<<endl;
}

那就有意义了。