C语言 DLL 回调函数,C# 调用 C++ DLL 回调函数
C++ library
library.h
#ifndef __LIBRARY_H__
#define __LIBRARY_H__
//exports.def
#ifdef __cplusplus //__cplusplus是cpp中自定义的一个宏
extern "C" { //告诉编译器，这部分代码按C语言的格式进行编译，而不是C++的
#endif
#define LIB_EXPORTS __declspec(dllexport)
// 回调函数必须指定 __stdcall， 否则C#调用会闪退
typedef void(__stdcall *OnConnected)(int code, int msg);
void connect(char* url, OnConnected onConnected);
// 可以.def文件导出库，也可以使用 __declspec(dllexport) 指定
//LIB_EXPORTS void show_info();
void show_info();
int add(int a, int b);
#ifdef __cplusplus
}
#endif
#endif//__LIBRARY_H__
library.cpp
#include "library.h"
#include
void show_info() {
printf("### library => show_info() ###\n");
}
void connect(char* url, OnConnected onConnected){
printf("### connect to %s ###\n", url);
onConnected(1, 2);
printf("### connected success ###\n");
return;
}
int add(int a, int b) {
return a + b;
}
exports.def
LIBRARY library
EXPORTS
show_info=show_info
add=add
connect=connect
C# 调用 C++ library
library.cs
using System.Runtime.InteropServices;
namespace echo_csharp
{
class library
{
public delegate void MyOnConnected(int code, int msg);
//public static OnConnected onConected;
[DllImport("library.dll", EntryPoint = "connect", CharSet = CharSet.Unicode, ExactSpelling = true, SetLastError = true, CallingConvention = CallingConvention.Cdecl)]
public static extern int connect(string url, MyOnConnected f);
[DllImport("library.dll", EntryPoint = "add", CharSet = CharSet.Unicode, ExactSpelling = true, SetLastError = true, CallingConvention = CallingConvention.Cdecl)]
public static extern int add(int a, int b);
[DllImport("library.dll", EntryPoint = "show_info", CharSet = CharSet.Unicode, ExactSpelling = true, SetLastError = true, CallingConvention = CallingConvention.Cdecl)]
public static extern void show_info();
}
}
Program.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace echo_csharp
{
class Program
{
static void myOnConnected(int code, int msg){
Console.WriteLine("myOnConnected");
Console.ReadLine();
}
static void Main(string[] args)
{
Console.WriteLine("add 1, 2 = "+library.add(1,2));
library.show_info();
Console.WriteLine("hello");
Console.ReadLine();
library.connect("http://www.cloudtalkers.com", myOnConnected);
Console.WriteLine("###############");
Console.ReadLine();
}
}
}
C++ 结构体指针传递
c++ 代码
typedef struct _Person
{
char name[128];
int age;
}Person
__declspec(dllexport) void GetPerson(Person *p);
对应的C# 代码
[StructLayout(LayoutKind.Sequential)]
public struct Person
{
[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 128)]
string name;
int age;
}
void GetPerson(ref Person p);
调用 GetPerson
Person p = new Person();
GetPerson(ref p);
struct 返回值问题