如何用C语言封装 C++的类，在 C里面使用

来源：互联网发布：乌镇互联网大会知乎编辑：程序博客网时间：2024/05/19 05:34

本文给出了一种方法。基本思想是，写一个 wrapper文件，把 C++类封装起来，对外只提供C语言的接口，和 C++i相关的都在 wrapper的实现文件里实现。

apple.h

#ifndef __APPLE_H__  #define __APPLE_H__  class Apple  {  public:      enum      {          APPLE_COLOR_RED,          APPLE_COLOR_BLUE,          APPLE_COLOR_GREEN,      };        Apple();      int GetColor(void);      void SetColor(int color);  private:      int m_nColor;  };  #endif

apple.cpp:

#include "apple.h"  Apple::Apple():m_nColor(APPLE_COLOR_RED)  {  }    void Apple::SetColor(int color)  {      m_nColor = color;  }    int Apple::GetColor(void)  {      return m_nColor;  }

AppleWrapper.h

#ifndef _APPLE_WRAPPER_H__  #define _APPLE_WRAPPER_H_  struct tagApple;  #ifdef __cplusplus  extern "C" {  #endif  struct tagApple *GetInstance(void);  void ReleaseInstance(struct tagApple **ppInstance);  extern void SetColor(struct tagApple *pApple, int color);  extern int GetColor(struct tagApple *pApple);  #ifdef __cplusplus  };  #endif  #endif

AppleWrapper.cpp

#include "AppleWrapper.h"  #include "apple.h"    #ifdef __cplusplus  extern "C" {  #endif  struct tagApple  {      Apple apple;  };  struct tagApple *GetInstance(void)  {      return new struct tagApple;  }  void ReleaseInstance(struct tagApple **ppInstance)  {      delete *ppInstance;      *ppInstance = 0;        }  void SetColor(struct tagApple *pApple, int color)  {      pApple->apple.SetColor(color);  }    int GetColor(struct tagApple *pApple)  {      return pApple->apple.GetColor();  }  #ifdef __cplusplus  };  #endif

test.c

#include "AppleWrapper.h"  #include <assert.h>    int main(void)  {      struct tagApple * pApple;      pApple= GetInstance();      SetColor(pApple, 1);      int color = GetColor(pApple);      printf("color = %d\n", color);      ReleaseInstance(&pApple);      assert(pApple == 0);      return 0;  }

可以用 GCC编译：

g++ -c apple.cpp  g++ -c apple.cpp  AppleWrapper.cpp  gcc test.c -o test AppleWrapper.o apple.o -lstdc++

其实， wrapper里的 struct 完全可以不要，定义一个 handle更好：

#ifndef _APPLE_WRAPPER_H__  #define _APPLE_WRAPPER_H_  #ifdef __cplusplus  extern "C" {  #endif  int  GetInstance(int *handle);  void ReleaseInstance(int *handle);  extern void SetColor(int handle, int color);  extern int GetColor(int handle);  #ifdef __cplusplus  };  #endif  #endif

#include "AppleWrapper.h"  #include "apple.h"  #include <vector>    #ifdef __cplusplus  extern "C" {  #endif    static std::vector<Apple *> g_appleVector;    int GetInstance(int * handle)  {      g_appleVector[0] =  new Apple;      *handle = 0;      return 1;  }  void ReleaseInstance(int *handle)  {      delete g_appleVector[*handle];      *handle = -1;        }  void SetColor(int handle, int color)  {      g_appleVector[handle]->SetColor(color);  }    int GetColor(int handle)  {      return g_appleVector[handle]->GetColor();  }  #ifdef __cplusplus  };  #endif

转载地址：

http://blog.csdn.net/caspiansea/article/details/9676153

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