C ++链接器错误（“链接器命令失败，退出代码为1”）

Question

I'm working on a project and keep getting a linker error, even though there is essentially no executable code thus far. The error message is below, and from what I gather, it has to do with the overloaded assignment operator, which I have not defined yet.

I can elaborate further through private messages, or if you would like to see the code. This is due to my school's academic integrity policy, and I do not wish to be expelled!

Thanks in advance!

---

Invoking: MacOS X C++ Linker

g++ -o "ProjectName" ./Class.o ./ProjectName.o
Undefined symbols for architecture x86_64:

"Class::operator=(Class const&)", referenced from:

  Class::Class(Class const&) in Class.o

ld: symbol(s) not found for architecture x86_64

clang: error: linker command failed with exit code 1 (use -v to see invocation)

make: *** [ProjectName] Error 1

** UPDATE **

If you see "Class" as a class name anywhere that means I forgot to change it back to the real class name, which is ShirtOrder.

Here is the code in my main cpp file:

#include <iostream>
#include <fstream>
#include <iomanip>
#include <string>
#include <cmath>
#include "ShirtOrder.h"

using namespace std;


/*********************************************************************************************************************
 ***************** FUNCTION PROTOTYPES -- FUNCTION PROTOTYPES -- FUNCTION PROTOTYPES -- FUNCTION PROTOTYPES **********
 *********************************************************************************************************************/

bool uploadFile(string fName, unsigned long &count, ShirtOrder* &head);
void clearLL(unsigned long &count, ShirtOrder* &head);
void summaryByMethod(unsigned long count, ShirtOrder* head);
void summaryByRegion(unsigned long count, ShirtOrder* head);

/*********************************************************************************************************************
 ***************** MAIN FUNCTION -- MAIN FUNCTION -- MAIN FUNCTION -- MAIN FUNCTION -- MAIN FUNCTION *****************
 *********************************************************************************************************************/

int main(int argc, char* argv[])
{
    if (argc < 2) // if only command line argument is program name
    {
        cout << "No file name entered." << endl;
    }

    else
    {
        ShirtOrder object;
        cout << "Test run" << endl;
    }
    return 0;
}

/**********************************************************************************************************
 ************ FUNCTION IMPLEMENTATIONS -- FUNCTION IMPLEMENTATIONS -- FUNCTION IMPLEMENTATIONS ************
 **********************************************************************************************************/

bool uploadFile(string fName, unsigned long &count, ShirtOrder* &head)
{
    return true;
}

void clearLL(unsigned long &count, ShirtOrder* &head)
{

}

void summaryByMethod(unsigned long count, ShirtOrder* head)
{

}

void summaryByRegion(unsigned long count, ShirtOrder* head)
{

}

my ShirtOrder.h file:

#ifndef SHIRTORDER_H_
#define SHIRTORDER_H_

#include <iostream>
#include <fstream>
#include <string>
#include <cmath>
#include <iomanip>

using namespace std;

class ShirtOrder
{
    friend ostream& operator<<(ostream &os, const ShirtOrder &rhsObj);

private:
    // the data members below are required (you may change identifiers)
    // there is no need for additional data members
    int orderYear, orderMonth, orderDay;
    char printMethod; // 's', 'i', or 'e'
    string message;
    int mediums; // number of medium shirts ordered
    int larges; // number of large shirts ordered
    int xls; // number of XL shirts ordered
    string shirtColor;
    string inkColor;
    string orderID;
    string region;
    string nameAndEmail;

    ShirtOrder* next; // new for P5

public:
    ShirtOrder(); // default constructor

    ShirtOrder(int orderYear, int orderMonth, int orderDay,
               char printMethod, string message, int mediums, int larges, int xls,
               string shirtColor, string inkColor, string orderID,
               string region, string nameAndEmail,
               ShirtOrder *soPtr = NULL);

    ShirtOrder(const ShirtOrder &otherObj);

    ~ShirtOrder(); // destructor                      // New for P5 (may not be in-line)

    ShirtOrder* getNext() const {return next;}        // New for P5 (may be in-line)

    void setNext(ShirtOrder* soPtr) {next = soPtr;}   // New for P5 (may be in-line)

    ShirtOrder operator=(const ShirtOrder &rhsObj);   // New for P5 (may not be in-line)

    double getBlankCost() const;
    double getPrintingCost() const;
    double getTotalCost() const;

    int    getLetterCount() const;
    char   getPrintMethod() const {return printMethod;}
    int    getOrderYear() const {return orderYear;}
    int    getOrderMonth() const {return orderMonth;}
    int    getOrderDay() const {return orderDay;}
    int    getMediums() const {return mediums;}
    int    getLarges() const {return larges;}
    int    getXls() const{return xls;}

    string getShirtColor() const {return shirtColor;}
    string getInkColor() const {return inkColor;}
    string getOrderID() const {return orderID;}
    string getRegion() const {return region;}
    string getNameAndEmail() const {return nameAndEmail;}
    string getMessage() const {return message;}

    void  setOrderYear (int orderYear) {this->orderYear = orderYear;}
    void  setOrderMonth (int orderMonth) {this->orderMonth = orderMonth;}
    void  setOrderDay (int orderDay) {this->orderDay = orderDay;}
    void  setPrintMethod (char printMethod) {this->printMethod = printMethod;}
    void  setMessage (string message) {this->message = message; }
    void  setMediums (int mediums) {this->mediums = mediums;}
    void  setLarges (int larges) {this->larges = larges;}
    void  setXls (int xls) {this->xls = xls;}
    void  setShirtColor (string shirtColor) {this->shirtColor = shirtColor;}
    void  setInkColor (string inkColor) {this->inkColor = inkColor;}
    void  setOrderID (string orderID) {this->orderID = orderID;}
    void  setRegion (string region) {this->region = region;}
    void  setNameAndEmail (string nameAndEmail) {this->nameAndEmail = nameAndEmail;}

}; // end declaration of class ShirtOrder

/******************************************************************************************
 *********** MEMBER FUNCTION IMPLEMENTATIONS -- MEMBER FUNCTION IMPLEMENTATIONS ***********
 ******************************************************************************************/

#endif /* SHIRTORDER_H_ */

my ShirtOrder.cpp file:

#include "ShirtOrder.h"
#include <iostream>
#include <string>
#include <fstream>
#include <vector>

using namespace std;

/******************************************************************************************
 *********** MEMBER FUNCTION IMPLEMENTATIONS -- MEMBER FUNCTION IMPLEMENTATIONS ***********
 ******************************************************************************************/

// Default Constructor
ShirtOrder::ShirtOrder()
{
    orderYear = 0;
    orderMonth = 0;
    orderDay = 0;
    printMethod = 'x'; // 's', 'i', or 'e'
    message = "";
    mediums = 0; // number of medium shirts ordered
    larges = 0; // number of large shirts ordered
    xls = 0; // number of XL shirts ordered
    shirtColor = "";
    inkColor = "";
    orderID = "";
    region = "";
    nameAndEmail = "";

    next = NULL;

    cout << "Default constructor has run" << endl;
}

// Other Constructor
ShirtOrder::ShirtOrder(int orderYear, int orderMonth, int orderDay,
        char printMethod, string message, int mediums, int larges, int xls,
        string shirtColor, string inkColor, string orderID,
        string region, string nameAndEmail, ShirtOrder *soPtr)
{
    this-> orderYear = orderYear;
    this->orderMonth = orderMonth;
    this->orderDay = orderDay;
    this->printMethod = printMethod; // 's', 'i', or 'e'
    this->message = message;
    this->mediums = mediums; // number of medium shirts ordered
    this->larges = larges; // number of large shirts ordered
    this->xls = xls; // number of XL shirts ordered
    this->shirtColor = shirtColor;
    this->inkColor = inkColor;
    this->orderID = orderID;
    this->region = region;
    this->nameAndEmail = nameAndEmail;

    next = NULL;

    cout << "Constructor Numero Dos has run" << endl;
}

// Other, other constructor
ShirtOrder::ShirtOrder(const ShirtOrder &otherObj)
{
    ShirtOrder object;
    object = otherObj;
    object.orderYear = otherObj.orderYear;
    object.orderMonth = otherObj.orderMonth;
    object.orderDay = otherObj.orderDay;
    object.printMethod = otherObj.printMethod;
    object.message = otherObj.message;
    object.mediums = otherObj.mediums;
    object.larges = otherObj.larges;
    object.xls = otherObj.xls;
    object.shirtColor = otherObj.shirtColor;
    object.inkColor = otherObj.inkColor;
    object.orderID = otherObj.orderID;
    object.region = otherObj.region;
    object.nameAndEmail = otherObj.nameAndEmail;
    object.next = otherObj.next;

    cout << "Constructor Numero Tres has run" << endl;
}

// DESTRUCTOR
ShirtOrder::~ShirtOrder()
{
    cout << "Destructor has run" << endl;
}

ShirtOrder operator=(const ShirtOrder &rhsObj)
{

}

// COME BACK TO REMOVE WHITESPACE
int ShirtOrder::getLetterCount() const
{
    string tempMessage = getMessage();

    int pos1 = tempMessage.find("\"") + 1; // find first occurrence of a double quotation mark and assign position +1 value to pos1
    int pos2 = tempMessage.rfind("\"") - 1; // find last occurrence of a double quotation mark and assign position -1 value to pos2

    tempMessage = tempMessage.substr(pos1, (pos2 - pos1)); // sets variable tempMessage to string between quotation marks

    return tempMessage.length();
}

double ShirtOrder::getBlankCost() const
{
    return 0.0;
}

double ShirtOrder::getPrintingCost() const
{
    return 0.0;
}

double ShirtOrder::getTotalCost() const
{
    return 0.0;
}

Answer 1

Linker is telling you that Class::Class(Class const&) is missing from your Class.cpp

You either need to remove its declaration from your Class.h or add implementation in your Class.cpp.

The error that you originally reported doesn't quit match with the code. Anyways, these are the issues that you have:

• Incorrect return of assignment operator: ShirtOrder operator=(const ShirtOrder &rhsObj) (should be ShirtOrder& )
• Implementation of operator= is empty, you should assign members and then return *this ;
• Your operator= is defined as ShirtOrder& ShirtOrder::operator=(const ShirtOrder &rhsObj) , while it has to be this in .cpp file: ShirtOrder& ShirtOrder::operator=(const ShirtOrder &rhsObj)
• Your copy constructor ShirtOrder::ShirtOrder(const ShirtOrder &otherObj) doesn't have correct implementation. it has to assign all these values to this-> instead of object.