[C++知识库]C#调用C++dll中的非托管类方法（stdcall）

1 新建C++ dll项目

#pragma once
class COperation
{
public:
	int Add(int a, int b);
	int Avg(int* buf, int count);
};

#include "pch.h"
#include "COperation.h"

int COperation::Add(int a, int b)
{
    return a+b;
}

int COperation::Avg(int* buf, int count)
{
    int sum = 0;
    for (size_t i = 0; i < count; i++)
    {
        sum += buf[i];
    }
    return sum/count;
}

2 建一个COperationInterface类

#pragma once
namespace OperationInterface
{
	extern "C" __declspec(dllexport) int __stdcall Add(int a, int b);
	extern "C" __declspec(dllexport) int __stdcall Avg(int* buf, int count);

}

#include "pch.h"
#include "COperationInterface.h"
#include "COperation.h"

COperation op;

int __stdcall OperationInterface::Add(int a, int b)
{
	return op.Add(a,b);
}

int __stdcall OperationInterface::Avg(int* buf, int count)
{
	return op.Avg(buf,count);
}

3 生成dll，lib

4 新建C#控制台项目TestDLL,将上面生成的dll拷贝到项目debug目录下，修改程序

using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading.Tasks;

namespace TestDLL
{
    class Program
    {
        [DllImport("DLL.dll")]
        public extern static int Add(int a, int b);


        [DllImport("DLL.dll")]
        public extern static int Avg(int[] buf, int count);
        static void Main(string[] args)
        {
            int res = Add(2, 3);
            int[] buf = { 1, 2, 3, 4, 5 };
            res = Avg(buf, 5);
        }
    }
}

运行即可