[英]C code with C++ data structures
I know that this is not a good way of developing of a project, but for some reasons of my work I am committed to integrate some data structures in C++ (LRU cache and hash map) in a C project. 我知道这不是开发项目的好方法,但由于我工作的一些原因,我致力于在C项目中集成C ++(LRU缓存和哈希映射)中的一些数据结构。
So far I know that there is some way to call C functions in C++ using extern "C"
, but what about calling C++ objects (methods...) from C? 到目前为止,我知道有一些方法可以使用extern "C"
在C ++中调用C函数,但是从C调用C ++对象(方法......)呢?
I am using GCC. 我正在使用GCC。
Write a C wrapper around your C++ interface. 在C ++接口周围编写一个C包装器。 Compile it as C++, but make sure to include your C interface in an extern "C"
block. 将其编译为C ++,但请确保将C接口包含在extern "C"
块中。 This new interface should link fine with your C program and provide you with access to your C++ code. 这个新界面应与您的C程序良好链接,并为您提供对C ++代码的访问。
If all the code is being compiled with C++ compiler there should be no (or very little) problem. 如果使用C ++编译器编译所有代码,则应该没有(或很少)问题。
If you have C compiled with gcc and C++ compiled with g++ then you need to write a header wrapper around your class to make the C++ code visable via a set of functions. 如果您使用gcc编译的C和使用g ++编译的C ++,那么您需要在类周围编写一个包装器,以通过一组函数使C ++代码可见。
Example: 例:
MyClass.h MyClass.h
#ifdef __cplusplus
class MyClass
{
public:
MyClass() {/*STUFF*/}
~MyClass() {/*STUFF*/}
int doStuff(int x, float y) {/*STUFF*/}
};
extern "C" {
#endif
/* C Interface to MyClass */
void* createMyClass();
void destroyMyClass(void* mc);
int doStuffMyClass(void* mc, int x, float y);
#ifdef __cplusplus
}
#endif
Source File 源文件
MyClass.cpp MyClass.cpp
#include "MyClass.h"
void* createMyClass() {return reinterpret_cast<void*>(new MyClass);}
void destroyMyClass(void* mc) {delete reinterpret_cast<MyClass*>(mc);}
int doStuffMyClass(void* mc, int x, float y)
{
return reinterpret_cast<MyClass*>(mc)->doStuff(x,y);
}
Your C code now just include "MyClass.h" and uses the C functions provided. 您的C代码现在只包含“MyClass.h”并使用提供的C函数。
MyCFile.c MyCFile.c
#include "MyClass.h"
int main()
{
void* myClass = createMyClass();
int value = doStuffMyClass(myClass, 5, 6.0);
destroyMyClass(myClass);
}
You need to create C compatible forwarding functions that take as their first parameter a pointer to the object. 您需要创建C兼容的转发函数,将第一个参数作为指向对象的指针。 The forwarding function will then [typically] cast the first parameter to the correct object type and call the appropriate member function. 然后,转发功能[通常]将第一个参数转换为正确的对象类型并调用适当的成员函数。
// Function declaration in header
extern "C" void function(void *object, int param1, int param2);
// Function definition in source file
extern "C" function(void *object, int param1, int param2)
{
static_cast<Object*>(object)->member_function(param1, param2);
}
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