在C ++中从另一个源访问类，会初始化构造函数 [英] Accessing classes from another source in C++, issues initializing the constructor

问题描述

我有一个名为Player的类，它有一个构造函数，它在我的player.h文件中声明了5个float参数，然后在我的player.cpp文件中初始化，如帖子底部所示。

I have a class called Player that has a constructor that takes 5 float parameters declared in my "player.h" file and then initialized in my "player.cpp" file as shown at the bottom of the post.

每当我尝试运行程序时，都会出现错误：

Whenever I try to run the program, I get the error:

build/Debug/MinGW-Windows/player.o: In function `Player':
C:\Users\User\Dropbox\NetBeans Workspace\Testing/player.cpp:11: multiple definition of `Player::Player(float, float, float, float, float)'
build/Debug/MinGW-Windows/main.o:C:\Users\User\Dropbox\NetBeans Workspace\Testing/player.h:20: first defined here

我在这里做错了什么？我试图摆脱公共：之前的构造函数，但这没有帮助。它说我有多个定义的构造函数，但我只初始化它一次。我相信这是明显的事情。

What am I doing wrong here? I tried getting rid of the "public:" before the constructor, but that didn't help at all. It says I have multiple definitions of the constructor, but I only initialize it once. I am sure it is something obvious.

这两个文件的完整源代码：

The complete source of the two files:

player.cpp

#include "player.h"

Player::Player(float x, float y, float z, float rx, float ry) {

}

player.h

#ifndef PLAYER_H
#define PLAYER_H

class Player {

public:

    Player(float x, float y, float z, float rx, float ry);
};

#endif

推荐答案

可能没有保护您的 .h 文件。

You probably haven't protected your .h file.

您包括您的 player.h c> 中，它为此编译单元获取一个定义。
然后它包含在 player.cpp 中，它获得第二个定义。

You include your player.h in main.cpp, there it gets one definition for this compilation unit. And then it's included in player.cpp, where it gets a second definition.

编译器不支持 #pragma once ，您必须使用古典手动保护它们：

If your compiler doesn't support #pragma once, you'll have to manually protect them with the classical :

#ifndef PLAYER_H
#define PLAYER_H

// all your class definition code here

#endif

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