c++ - 在Days.obj中已经定义了奇怪的错误 “float percentOfOres”(？percentOfOres @@ 3MA)

Question

我是C++的新手，正在编写一个简单的角色扮演采矿游戏。我只编码了几周，但遇到了一个错误，该错误已经处理了好几天，但仍然没有解决任何问题。我什至考虑过只是取消程序然后重试。我有4个文件:Game.cpp，header.h，nuggetsFound.cpp和days.cpp。我试图拥有一个可以在整个文件中更改的全局变量，但是，即使我什至没有重新定义什么内容，我仍然会遇到这个疯狂的错误，提示“float percentOfOres”(？percentOfOres @@ 3MA)已经在Days.obj中定义。其中所有我的变量和文件都会 pop 其中的几个，而且我快要疯了。我只有13岁，所以我不能总是得到我需要的所有帮助，所以如果你们能帮助我，我将非常感谢。谢谢! (我排除了nuggetsFound.cpp，因为它与days.cpp的情况基本相同。game.cpp中还有很多代码，但我只包含了我认为相关的代码。这是两个文件

game.cpp
#include <iostream>
#include <string>
#include <stdlib.h>
#include <windows.h>
#include <cstdlib>
#include <ctime>
#include "Header.h"
using namespace std;
float netWorth{ 0.0 };
float salary{ 0.0 };
float percentOfOres{ 0.0 };

int main()
{
    cout << "Welcome to Miner Man!\n";
    cout << "Press any key and press enter to continue";days.cpp

#include "game.cpp"


using namespace std;

void days()
{
    for (int iii{ 1 }; iii <= 5; iii++)
    {
        cout << "Net Worth: " << netWorth << "\tSalary: " << salary << 
"\tPercent of Ores: " << percentOfOres;
        cout << "\n";
        cout << "CCCCCCCCCCCCCCCCCCCCCCCCCCCCC\n";
        cout << "CCCCCCCCCCCCC\n";
        cout << "CCCCCCCC\n";
        cout << "CCCC            ///////\n";
        cout << "CCC             |O  O |\n";
        cout << "CC              | __  |\n";
        cout << "C              asssssssa\n";
        cout << "C            a  sssssss  a\n";
        cout << "C           a   sssssss   a\n";
        cout << "           a    sssssss   a\n";
        cout << "C         h     sssssss   a\n";
        cout << "C p      h      sssssss    \n";
        cout << "C  p    h       l     l\n";
        cout << "CC  p  h      p l     l\n";
        cout << "CCC   p p p p___l     l___\n";
        cout << "CCCCC       L___l     l___l\n";
        cout << "CCCCCCCCCCCCCCCCCCCCCCCCCCCCC\n";
        Sleep(500);
        system("cls");

        cout << "Net Worth: " << netWorth << "\tSalary: " << salary << 
"\tPercent of Ores: " << percentOfOres;
        cout << "\n";
        cout << "CCCCCCCCCCCCCCCCCCCCCCCCCCCCC\n";
        cout << "CCCCCCCCCCCCC\n";
        cout << "CCCCCCCC\n";
        cout << "CCCC  p         ///////\n";
        cout << "CCC  p          |O  O |\n";
        cout << "CC  p           | __  |\n";
        cout << "C   phhhhhhaaaa sssssssa\n";
        cout << "C   p           sssssss  a\n";
        cout << "C    p          sssssss   a\n";
        cout << "C     p         sssssss   a\n";
        cout << "C               sssssss   a\n";
        cout << "C               sssssss    \n";
        cout << "C               l     l\n";
        cout << "CC              l     l\n";
        cout << "CCC          ___l     l___\n";
        cout << "CCCCC       L___l     l___l\n";
        cout << "CCCCCCCCCCCCCCCCCCCCCCCCCCCCC\n";
        Sleep(500);
        system("cls");
    }
}

#pragma once
#include <iostream>
#include <string>
#include <stdlib.h>
#include <windows.h>
#include <cstdlib>
#include <ctime>
#include "data.hpp"
using namespace std;



void days();
void endOfDayNugs();


void endOfDayNugs()
{
    srand((unsigned)time(0));
    int silverFoundToday = rand() % 25;

    srand((unsigned)time(0));
    int goldFoundToday = rand() % 10;

    srand((unsigned)time(0));
    int diamondsFoundToday = rand() % 5;

    if (silverFoundToday == 0)
    {
        cout << "Sorry, you found no Silver today\n";
        Sleep(3000);
        system("cls");
    }
    else if (silverFoundToday > 0)
    {
        for (int sss{ 1 }; sss < 3; sss++)
        {
            cout << "You found " << silverFoundToday << " silver!\n";
            cout << "\n/SSSSSS\\\n";
            Sleep(500);
            system("cls");
        }

        if (percentOfOres == 0)
        {
            cout << "You don't make any money of your silver yet, but                 continue working towards that promotion!";
            Sleep(5000);
            system("cls");
        }
        else if (percentOfOres > 0)
        {
            cout << "You made " << percentOfOres * silverFoundToday <<         "dollers off of your silver\n";
            netWorth += percentOfOres * silverFoundToday;
            Sleep(5000);
            system("cls");
        }
    }
    if (goldFoundToday == 0)
    {
        cout << "Sorry, you found no gold today\n";
        Sleep(3000);
        system("cls");
    }
    else if (goldFoundToday > 0)
    {
        for (int ggg{ 1 }; ggg < 3; ggg++)
        {
        cout << "You found " << goldFoundToday << " gold!\n";
        cout << "\n/GGGGGG\\\n";
        Sleep(500);
        system("cls");
    }

    if (percentOfOres == 0)
    {
        cout << "You don't make any money of your gold yet, but continue working towards that promotion!";
        Sleep(5000);
        system("cls");
    }
    else if (percentOfOres > 0)
    {
        cout << "You made " << percentOfOres * goldFoundToday << "dollers off of your gold\n";
        netWorth += percentOfOres * goldFoundToday;
        Sleep(5000);
        system("cls");
    }
}
if (diamondsFoundToday == 0)
{
    cout << "Sorry, you found no diamonds today\n";
    Sleep(3000);
    system("cls");
}
else if (diamondsFoundToday > 0)
{
    for (int ddd{ 1 }; ddd < 3; ddd++)
    {
        cout << "You found " << diamondsFoundToday << " diamonds!\n";
        cout << "\n/DDDDDD\\\n";
        Sleep(500);
        system("cls");
    }

    if (percentOfOres == 0)
    {
        cout << "You don't make any money of your diamonds yet, but continue working towards that promotion!";
        Sleep(5000);
        system("cls");
    }
    else if (percentOfOres > 0)
    {
        cout << "You made " << percentOfOres * diamondsFoundToday << "dollers off of your diamonds\n";
        netWorth += percentOfOres * diamondsFoundToday;
        Sleep(5000);
        system("cls");
    }
}

}

Answer 1

任何全局的东西都需要声明，但是没有在头文件中定义。

将头文件包含到您的.cpp文件中。

不要将.cpp文件包括到其他.cpp文件中。

在一个.cpp文件中声明头文件中的所有内容。

声明说“这个东西存在于某处”，定义说“使这个东西存在”。 C++具有一定义规则，该规则指出整个程序中可能仅存在针对特定事物的一个定义。1

如果将定义放在头文件中并将其包含在两个.cpp文件中，则该定义在程序中存在两次(每个.cpp文件一次)，这就是导致错误的原因。

以下是一些声明示例:

void foo();       // function declaration
extern float bar; // variable declaration

以下是一些定义示例:

void foo() { }       // function definition
float bar;           // global variable definition
static float widget; // local variable definition

因此，在您的.h文件中，您应该声明变量，但不要定义变量:

extern float netWorth;
extern float salary;
extern float percentOfOres;

然后在您的一个.cpp文件中，定义它们:

float netWorth{ 0.0 };
float salary{ 0.0 };
float percentOfOres{ 0.0 };

可以将仅在一个.cpp文件中使用的所有顶级变量(在函数外部声明的那些顶级变量)声明为 static。这些变量被认为是该编译单元的隐藏实现细节，在外部将不可见。

也就是说，您可以在两个不同的.cpp文件中包含 static float foo;而不违反一定义规则。但是，请注意，每个文件的 foo都引用不同的变量!

1此规则有一些异常(exception)。特别是，声明为 inline的函数可能存在于多个编译单元中，链接器将选择其中一个，而丢弃其他一个。