C ++私有静态成员变量

本文介绍了C ++私有静态成员变量的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

此C ++代码在编译时产生链接器错误:

This C++ code is producing linker errors at compile time:

// A.h class A { public: static void f(); private: static std::vector<int> v; }; // A.cpp void A::f() { // this line is causing trouble int i = v.size(); }

将向量声明移动到cpp文件中即可.但是，我想了解以上代码中的链接器错误"Undefined symbols"原因.是什么导致上述代码中的链接器错误?

Moving the vector declaration into the cpp file works. However I want to understand the linker error "Undefined symbols" cause in the above code. What is causing the linker error in the above code?

推荐答案

静态成员必须在编译单元中定义:

Static members have to be defined in a compilation unit:

// A.cpp vector<int> A::v;