C++接口编译

Question

编辑：

我想出了解决办法。我没有将-combine添加到编译指令中，这会产生错误。

我正在阅读Deitel和Deitel的“如何编程”( C++ How to Program )一书，并在使用g++构建和编译C++界面时遇到了问题。问题是，我已经在.h文件中声明了类，并在.cpp文件中定义了实现，但是当我试图编译我编写的测试文件时，我想不出如何让它编译和工作。我收到的g++错误是：

Undefined symbols:
  "GradeBook::GradeBook(std::basic_string<char, std::char_traits<char>, std::allocator<char> >)", referenced from:
      _main in ccohy7fS.o
      _main in ccohy7fS.o
  "GradeBook::getCourseName()", referenced from:
      _main in ccohy7fS.o
      _main in ccohy7fS.o
ld: symbol(s) not found
collect2: ld returned 1 exit status<

如果有人能给我指明正确的方向，我会感激的。

我的头文件：

//Gradebook 6 Header
//Purpose is to be the class declaration for the class Gradebook 6
//Declare public, privates, and function names. 

#include  //the standard c++ string class library
using std::string;

//define the class gradebook
class GradeBook
{
    public:  //all the public functions in the class

     GradeBook(string ); //constructor expects string input
     void setCourseName (string ); //method sets course name--needs string input
     string getCourseName(); //function returns a string value
     void displayMessage();  //to console

    private: //all private members of the class
        string courseName; 
}; //ends the class declaration 

我的.cpp文件是：

//Gradebook 6
// The actual implementation of the class delcaration in gradebook6.h

#include 
using std::cout;
using std::endl;

#include "gradebook6.h" //include the class definition

//define the class gradebook

GradeBook::GradeBook(string name) //constructor expects string input
{
    setCourseName(name); //call the set method and pass the input from the constructor. 
}

void GradeBook::setCourseName (string name) //method sets course name--needs string input
{
    courseName = name; //sets the private variable courseName to the value passed by name
}

string GradeBook::getCourseName() //function returns a string value
{
    return courseName;
}

void GradeBook::displayMessage()  //function does not return anything but displays //message to console
{
   cout //message here, the pre tag isn't letting it display
} //end function displayMessage

最后，我编写的测试文件实现了接口并对其进行了测试。

// Gradebook6 Test
// Program's purpose is to test our GradeBook5 header file and file seperated classes

#include 
using std::cout;
using std::endl;

#include "gradebook6.h" //including our gradebook header from the local file.

//being program
int main()
{
    //create two gradebook objects 
    GradeBook myGradeBook1 ("CSC 101 Intro to C++ Programming"); //create a default object using the default constructor
    GradeBook myGradeBook2 ("CSC 102 Data Structures in C++");

    //display intitial course name
    cout //another output message here that the code tag does not like

    return 0;
}

Answer 1

看起来，您只需将GradeBook.cpp对象文件中的链接链接到最终的可执行文件。介意张贴您的makefile或您正在构建它的方式？

Answer 2

您所看到的是链接器错误(此指示位于"ld返回“位: ld是链接器)。您需要将所有.cpp文件交给g++，以便编译和链接它们，或者使用后者的-c开关从.cpp生成.o，然后在进一步的g++命令上使用.o构建(链接)可执行文件。