c++ - Visual Studio 2010- fatal error LNK1120 : 1 unresolved externals; c++

Question

我遇到了错误:

asteroid.obj : error LNK2001: unresolved external symbol "private: static char (* Asteroid::Image)[4]" (?Image@Asteroid@@0PAY03DA) 1>C:\Users\john\Documents\Visual Studio 2010\Projects\assignment3.1\Debug\assignment3.1.exe : fatal error LNK1120: 1 unresolved externals

而且我在代码中看不出我的问题是什么。我的程序中唯一改变的是制作我的“Image”和“LoadImage”成员函数。

这就是我在头文件中的代码现在的样子(跳过一些公共(public)函数)

class Asteroid
{
private:
static const int ROWS = 3;
static const int COLUMNS = 4;
int row;
int column;
int row_size;
int column_size;
unsigned int ore_value;
static char Image[ROWS][COLUMNS];

public: static void LoadImage();
};

这就是 LoadImage() 函数在 .cpp 文件中的样子

void Asteroid::LoadImage()
{
string myline;
ifstream asteroid_image_data("asteroid.txt");
if (asteroid_image_data.fail())
{
    cerr << "Asteroid image file is not available" << endl;
    return;
}

for (unsigned int i = 0; i < ROWS; i++)
{
    getline(asteroid_image_data, myline, '\n');
    if (!asteroid_image_data)
    {
        cerr << "Asteroid image file is missing some data" << endl;
        return;
    }

    for (unsigned int j = 0; j < COLUMNS; j++)
    {
        Image[i][j] = myline[j];
    }
}
asteroid_image_data.close();
}

main.cpp 的调用就是

Asteroid::LoadImage();

Answer 1

You have to add a definition for the static char array

Here is how to do it in the header cpp file:

   char Asteroid::Image[3][4] = { {'0','0','0','0'},
                                  { '0','0','0','0'},
                                  { '0','0','0','0'}
                                };

或者

   char Asteroid::Image[3][4];

There is no problem like this, it works

Your header file (Header.h):

        #pragma once

        #include <string>

        using namespace std;

        class Asteroid
        {
        private:
            static const int ROWS = 3;
            static const int COLUMNS = 4;
            int row;
            int column;
            int row_size;
            int column_size;
            unsigned int ore_value;
            static char Image[ROWS][COLUMNS];

            public: static void LoadImage();
        };

Header.cpp:

#include "Header.h"
#include <fstream>
#include <iostream>

using namespace std;

void Asteroid::LoadImage()
{
    string myline;
    ifstream asteroid_image_data("asteroid.txt");

    if (asteroid_image_data.fail())
    {
        cerr << "Asteroid image file is not available" << endl;
        return;
    }

    for (unsigned int i = 0; i < ROWS; i++)
    {
        getline(asteroid_image_data, myline, '\n');

        if (!asteroid_image_data)
        {
            cerr << "Asteroid image file is missing some data" << endl;
            return;
        }

        for (unsigned int j = 0; j < COLUMNS; j++)
        {
            Image[i][j] = myline[j];
        }
    }
    asteroid_image_data.close();
}

char Asteroid::Image[3][4];

主文件(Source.cpp):

    #include <iostream>
    #include "Header.h""

    int main() {

        Asteroid::LoadImage();
    }