如何编写我的 C++ 函数以便我可以从 C# 调用它? [英] How to write my C++ function so I can call it from C#?

问题描述

我有 C++ 代码.该代码包含 Windows 移动 GPS 启用/禁用功能.我想从 C# 代码中调用该方法，这意味着当用户单击按钮时，C# 代码应该调用 C++ 代码.

I have C++ code. That code contains Windows mobile GPS enable/disable functionality. I want to call that method from C# code, that means when the user clicks on a button, C# code should call into C++ code.

这是用于启用 GPS 功能的 C++ 代码:

This is the C++ code for enabling the GPS functionality:

#include "cppdll.h"

void Adder::add()
{
// TODO: Add your control notification handler code here
  HANDLE hDrv = CreateFile(TEXT("FNC1:"), GENERIC_READ | GENERIC_WRITE,
                0, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
  if (0 == DeviceIoControl(hDrv, IOCTL_WID_GPS_ON, NULL, 0, NULL, 0, NULL, NULL))
  {
     RETAILMSG(1, (L"IOCTL_WID_RFID_ON Failed !! \r\n")); return;
  }
     CloseHandle(hDrv);

 return (x+y);
}

这是头文件cppdll.h:

class __declspec(dllexport) Adder
{
  public:
   Adder(){;};
  ~Adder(){;};
 void add();
};

如何使用 C# 调用该函数?

How can I call that function using C#?

请问，有人能帮我解决这个问题吗?

Please, can anybody help me out with this issue?

推荐答案

我举个例子.

你应该像这样声明你的 C++ 函数用于导出(假设最近的 MSVC 编译器):

You should declare your C++ functions for export like so (assuming recent MSVC compiler):

extern "C"             //No name mangling
__declspec(dllexport)  //Tells the compiler to export the function
int                    //Function return type     
__cdecl                //Specifies calling convention, cdelc is default, 
                       //so this can be omitted 
test(int number){
    return number + 1;
}

并将您的 C++ 项目编译为 dll 库.将项目目标扩展名设置为 .dll，将配置类型设置为动态库 (.dll).

And compile your C++ project as a dll library. Set your project target extension to .dll, and Configuration Type to Dynamic Library (.dll).

然后，在 C# 中声明:

Then, in C# declare:

public static class NativeTest
{
    private const string DllFilePath = @"c:\pathto\mydllfile.dll";

    [DllImport(DllFilePath , CallingConvention = CallingConvention.Cdecl)]
    private extern static int test(int number);

    public static int Test(int number)
    {
        return test(number);
    }
}

然后您可以按预期调用 C++ 测试函数.请注意，一旦您想传递字符串、数组、指针等，它可能会变得有点棘手.参见例如 this SO 问题.

Then you can call your C++ test function, as you would expect. Note that it may get a little tricky once you want to pass strings, arrays, pointers, etc. See for example this SO question.

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