System.EntryNotFoundException:无法在DLL中找到入口点

时间:2012-02-17 05:41:17

标签: c# c++ wpf visual-c++

我正在准备一个小的C ++ dll,其中的函数将从C#中调用。

DLLTestFile.h

#ifdef DLLFUNCTIONEXPOSETEST_EXPORTS
#define DLLFUNCTIONEXPOSETEST_API __declspec(dllexport)
#else
#define DLLFUNCTIONEXPOSETEST_API __declspec(dllimport)
#endif

extern "C" DLLFUNCTIONEXPOSETEST_API int fnSumofTwoDigits(int a, int b);

DLLTestfile.cpp

#include "stdafx.h"
#include "DLLFunctionExposeTest.h"
BOOL APIENTRY DllMain( HMODULE hModule,
                       DWORD  ul_reason_for_call,
                       LPVOID lpReserved
                     )
{
    return TRUE;
}
DLLFUNCTIONEXPOSETEST_API int fnSumofTwoDigits(int a, int b)
{
    return a + b;
}

C#项目:

static class TestImport
    {
        [DllImport("DLLFunctionExposeTest.dll", CallingConvention = CallingConvention.Cdecl, EntryPoint = "fnSumofTwoDigits")]
        public static extern int fnSumofTwoDigits(int a, int b);
    }
public partial class MainWindow : Window
    {
        int e = 3, f = 4;
        public MainWindow()
        {
            try
            {
            InitializeComponent();
            int g = TestImport.fnSumofTwoDigits(e, f);
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.ToString());
        }
    }
}

我收到异常:“System.EntryNotFoundException:无法在DLL中找到入口点”

我正在使用Visual Studio提供的默认模板,在创建新项目时,Visual C ++ - > Win32项目 - > DLL(选中导出符号)。有人可以为此建议解决方案。在找了很久之后,我一直无法找到问题。

3 个答案:

答案 0 :(得分:2)

对我来说很好,完整的文件供参考:

dllmain.cpp:

// dllmain.cpp : Defines the entry point for the DLL application.
#include "stdafx.h"
#include "DLL.h"

BOOL APIENTRY DllMain( HMODULE hModule,
                       DWORD  ul_reason_for_call,
                       LPVOID lpReserved
                     )
{
    return TRUE;
}

DLL_API int fnSumofTwoDigits(int a, int b)
{
    return a + b;
}

DLL.h:

// The following ifdef block is the standard way of creating macros which make exporting 
// from a DLL simpler. All files within this DLL are compiled with the DLL_EXPORTS
// symbol defined on the command line. This symbol should not be defined on any project
// that uses this DLL. This way any other project whose source files include this file see 
// DLL_API functions as being imported from a DLL, whereas this DLL sees symbols
// defined with this macro as being exported.
#ifdef DLL_EXPORTS
#define DLL_API __declspec(dllexport)
#else
#define DLL_API __declspec(dllimport)
#endif

extern "C" DLL_API int fnSumofTwoDigits(int a, int b);

Program.cs(为简单起见,Win32控制台应用程序):

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

namespace ConsoleApplication2
{
    class Program
    {
        [DllImport("C:\\Users\\Kep\\Documents\\Visual Studio 2010\\Projects\\SODLL\\Debug\\DLL.dll", CallingConvention = CallingConvention.Cdecl, EntryPoint = "fnSumofTwoDigits")]
        public static extern int fnSumofTwoDigits(int a, int b);

        static void Main(string[] args)
        {
            int A = fnSumofTwoDigits(3, 4);
            Console.WriteLine("A = " + A);
            Console.ReadLine();
        }
    }
}

答案 1 :(得分:1)

可能是您的C#进程以64位运行,而您的DLL是32位,反之亦然。当进程和DLL的位数不匹配时,我已经看到了这个问题。

答案 2 :(得分:0)

看起来您没有定义DLLFUNCTIONEXPOSETEST_EXPORTS,因此您使用import声明。测试使用dumpbin / exports以查看从dll导出的函数。

添加

#define DLLFUNCTIONEXPOSETEST_EXPORTS 1 
#include DLLTestFile.h