静态类成员上未解析的外部符号 [英] Unresolved external symbol on static class members

问题描述

非常简单的：

我有一个类主要由静态公共成员组成，所以我可以将类似的函数组合在一起，仍然必须从其他类/函数。

I have a class that consists mostly out of static public members, so I can group similar functions together that still have to be called from other classes/functions.

无论如何，我已经定义了两个静态unsigned字符在我的类的公共范围，当我试图修改这些值在同一个类的构造函数，我在编译时出现未解析的外部符号错误。

Anyway, I have defined two static unsigned chars in my class' public scope, when I try to modify these values in the same class' constructor, I am getting an "unresolved external symbol" error at compilation.

class test {

    public:

        static unsigned char X;
        static unsigned char Y;

        ...

        test();
};

test::test() {
    X = 1;
    Y = 2;
}

我是C ++的新手，为什么我不能这样做？

I'm new to C++ so go easy on me. Why can't I do this?

推荐答案

您忘记添加定义以匹配X和Y的声明

You forgot to add the definitions to match your declarations of X and Y

unsigned char test::X;
unsigned char test::Y;

您可能还需要初始化一个静态成员

somewhere. You might want to also initialize a static member

unsigned char test::X = 4;

并且，在定义中（通常在CXX文件中）它通常在.H文件中）

and again, you do that in the definition (usually in a CXX file) not in the declaration (which is often in a .H file)

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