Initializing a private static member variable in the cpp file. error: member is private

Question

这是一个简单的例子来说明我的问题。

IDGenerator.hpp

#ifndef IDGENERATOR_HPP_
#define IDGENERATOR_HPP_

class IDGenerator {

   private:
      static int s_nNextID;

      // make the IDGenerator class a static class with a private default constructor
      IDGenerator();

   public:
      static int GetNextID();

};

#endif

IDGenerator.cpp

#include "IDGenerator.hpp"

// initialize the static id
int IDGenerator::s_nNextID(1);

int GetNextID()
{
   return IDGenerator::s_nNextID++;
}

我已尝试显式初始化 (int IDGenerator::s_nNextID = 1;) 和隐式初始化，如图所示。这是编译命令和错误

g++ -c IDGenerator.cpp
IDGenerator.cpp: In function ‘int GetNextID()’:
IDGenerator.cpp:11:5: error: ‘int IDGenerator::s_nNextID’ is private
 int IDGenerator::s_nNextID(1);
     ^
IDGenerator.cpp:15:22: error: within this context
  return IDGenerator::s_nNextID++;

我也尝试过使用 -Wall 和 std=gnu++11 进行编译。同样的错误

Answer 1

错误与初始化无关。它只是指向初始化作为s_nNextID来自的点。

真正的错误在第 15 行，您从普通全局函数访问 s_nNextID 的地方，因为您忘记了 GetNextID.[=12 的定义头中的 IDGenerator:: =]

Answer 2

s_nNextID 是私有的，因此您不能像这样访问它。您需要使 GetNextID 成为 class IDGenerator 的成员。

Initializing a private static member variable in the cpp file. error: member is private

Initializing a private static member variable in the cpp file. error: member is private

c++

static

initialization

private