C++ 架构 x86_64 链接器错误的未定义符号

Question

I have a program where user enters the operations of a plane. User can select as many operations (holding, straight, landing etc.) as s/he wants. User can calculate the necessary fuel intake with operation 5.

I have applied to the Abstract Factory Design Pattern to the system as follows:

FlightModeInterface.h

class FlightModeInterface{

protected:
float time, fuel_rate, start, end, pace, distance;
float total;

public:
    enum FLIGHT_MODES{
        HOLDING,
        RAISING,
        LANDING,
        STRAIGHT
    };

    FlightModeInterface();

    virtual ~FlightModeInterface(){ }

    virtual float calcFuel(float, float, float,
              float, float, float) = 0;

    static FlightModeInterface* createFactory(FLIGHT_MODES);
};

FlightModeFactory.cpp

#include "FlightModeInterface.h"
#include "Holding.h"
#include "Landing.h"
#include "Raising.h"
#include "Straight.h"

class FlightModeFactory{
protected:
    float time, fuel_rate, start, end, pace, distance;
    float total;
public:
    static FlightModeInterface* createFactory(FlightModeInterface::FLIGHT_MODES mode){
        switch (mode) {
            case FlightModeInterface::HOLDING:
                return new Holding();
            case FlightModeInterface::LANDING:
                return new Landing();
            case FlightModeInterface::RAISING:
                return new Raising();
            case FlightModeInterface::STRAIGHT:
                return new Straight();
        }
        throw "invalid flight mode.";

    }
};

CalculateFuel.cpp

#include <iostream>
#include <stdio.h>
#include "FlightModeInterface.h"

using namespace std;


int main(){
    char op = 's';
    float time=0, fuel_rate=0, start=0, end=0, pace=0, distance=0;
    float total = 0;
    FlightModeInterface *factory;

    while(op != 'x') {

        float hold_result, raise_result, land_result, str_result;

        cout << "Please select an operation: " << endl;
        cout << "1 ---> Holding flight" << endl;
        cout << "2 ---> Raising" << endl;
        cout << "3 ---> Landing " << endl;
        cout << "4 ---> Straight " << endl;
        cout << "5 ---> Calculate total fuel consumption" << endl;
        cout << "x ---> Exit " << endl;

        cin >> op;

        switch(op){
        case '1':
            cout << "Holding time (minutes): ";
            cin >> time;
            cout << "Fuel rate (kg/sec): ";
            cin >> fuel_rate;

            factory = FlightModeInterface::createFactory(FlightModeInterface::HOLDING);

            hold_result = factory -> calcFuel(time, fuel_rate, 0, 0, 0, 0);

            total += hold_result;
            break;
        case '5':
            cout <<"Total fuel requirement: "<< total << " kg"<< endl;
            total = 0;
            break;
        case 'x':
            return 0;
        default:
            continue;
        }
    }
    return 0;

}

When I run CalculateFuel.cpp, I encounter this error (I use Eclipse Builder to build the code on MAC):

23:46:08 **** Build of configuration Debug for project CalculateFuel ****
make all 
Building file: ../src/CalculateFuel.cpp
Invoking: GCC C++ Compiler
g++ -O0 -g3 -Wall -c -fmessage-length=0 -MMD -MP -MF"src/CalculateFuel.d" -MT"src/CalculateFuel.d" -o "src/CalculateFuel.o" "../src/CalculateFuel.cpp"
Finished building: ../src/CalculateFuel.cpp

Building file: ../src/FlightModeFactory.cpp
Invoking: GCC C++ Compiler
g++ -O0 -g3 -Wall -c -fmessage-length=0 -MMD -MP -MF"src/FlightModeFactory.d" -MT"src/FlightModeFactory.d" -o "src/FlightModeFactory.o" "../src/FlightModeFactory.cpp"
Finished building: ../src/FlightModeFactory.cpp

Building target: CalculateFuel
Invoking: MacOS X C++ Linker
g++  -o "CalculateFuel"  ./src/CalculateFuel.o ./src/FlightModeFactory.o   
Undefined symbols for architecture x86_64:
  "FlightModeInterface::createFactory(FlightModeInterface::FLIGHT_MODES)", referenced from:
      _main in CalculateFuel.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: *** [CalculateFuel] Error 1

Any ideas on how to solve this?

Answer 1

FlightModeFactory.cpp 替换为 FlightModeFactory.h 后问题解决。