未解决的外部静态变量 [英] unresolved external with static variables

问题描述

我有一个名为 Pub 的类，它具有以下标题:

I have a class called Pub which has the following header:

#pragma once



class Pub
{

public:
    static double X_FACTOR;
    static double Y_FACTOR;
    static const int INIT_SCREEN_WIDTH=500;
    static const int INIT_SCREEN_HEIGHT=550;


    Pub(void);
    ~Pub(void);
};

我正在尝试使用以下内容在 main.cpp 中设置变量 Y_FACTOR:

I am trying to set the variable Y_FACTOR in main.cpp with the following:

Pub::Y_FACTOR=1.0;

是的，Pub.h 已正确包含，这可以证明我可以访问 INIT_SCREEN_WIDTH 和 INIT_SCREEN_HEIGHT但是，当我这样做时，会出现以下错误:

and yes Pub.h is included properly which can be demonstrated as I can access INIT_SCREEN_WIDTH and INIT_SCREEN_HEIGHT However when I do this I get the following error:

错误 6 错误 LNK2001: 无法解析的外部符号 "public: static双 Pub::Y_FACTOR"(?Y_FACTOR@Pub@@2NA) C:UsersPedro-Estevan-JuarezDocumentsVisual Studio2012ProjectsProject2Project2main.obj Project2 错误 7 错误LNK1120:1 个未解决的外部 C:UsersPedro-Estevan-JuarezDocumentsVisualStudio 2012ProjectsProject2DebugProject2.exe 1 1 Project2

Error 6 error LNK2001: unresolved external symbol "public: static double Pub::Y_FACTOR" (?Y_FACTOR@Pub@@2NA) C:UsersPedro-Estevan-JuarezDocumentsVisual Studio 2012ProjectsProject2Project2main.obj Project2 Error 7 error LNK1120: 1 unresolved externals C:UsersPedro-Estevan-JuarezDocumentsVisual Studio 2012ProjectsProject2DebugProject2.exe 1 1 Project2

我怀疑这是语法方面的问题，有人可以帮我解决这个问题吗?

I suspect this is something syntax wise, can someone please help me with this?

推荐答案

类定义中的代码只是一个声明.您需要在 cpp 文件中添加静态变量的定义.在使用它的任何函数之前，将其添加到您的 cpp 文件和文件范围内.

The code inside the class definition is just a declaration. You need to add definition of the static variable in a cpp file. Add this in your cpp file and in file scope before any function using it.

double Pub::Y_FACTOR;

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