执行构造函数时未分配全局 const 变量

Question

当我尝试在ProblemClass::ProblemClass() 中使用它时，没有分配MY_GLOBAL_CONST。为什么？如何解决？我正在处理一个旧的 VC6 MFC 项目。

SomeClass.h

#include "ProblemClass.h"
class SomeClass  
{
private:
    ProblemClass m_problemClass; //created on the heap

public:
    SomeClass();
    ~SomeClass();
}

ProblemClass.h

class ProblemClass
{
public:
    ProblemClass();
    ~ProblemClass();
}

ProblemClass.cpp

#include "ProblemClass.h"
const CString MY_GLOBAL_CONST = _T("User");//Also tried to put that line in ProblemClass.h without luck
ProblemClass::ProblemClass()
{
    CString foo = MY_GLOBAL_CONST; //MFC-Runtime assertion fails, MY_GLOBAL_CONST  is not assigned yet 
}
ProblemClass::~ProblemClass(){}

更新：

经过进一步调查，我可以确认 SomeClass 也在全局上下文中实例化。因此，Paul Sanders 说 “这里发生的是两个全局初始化程序以错误的顺序执行”是绝对正确的。

Answer 1

尝试替换：

const CString MY_GLOBAL_CONST = _T("User");

与：

const TCHAR MY_GLOBAL_CONST [] = _T("User");

后一种构造不需要任何运行时初始化，因此可以在其他初始化代码中依赖MY_GLOBAL_CONST（因为这里肯定会发生两个全局初始化程序以错误的顺序执行）。

Answer 2

我看起来您在声明中错过了 static 关键字。我需要在类外初始化的全局变量的秘诀。

头文件

class ProblemClass
{
public:
    ProblemClass();
    ~ProblemClass();

private:
    static const CString MY_GLOBAL_CONST; // declaration in the header file
}

源文件

const CString ProblemClass::MY_GLOBAL_CONST = _T("HELLO_WORLD"); // Initialization here outside of class

ProblemClass::ProblemClass()
{
    CString foo = MY_GLOBAL_CONST; //MFC-Runtime assertion fails, MY_GLOBAL_CONST  is not assigned yet 
}

// everything else