System.EntryNotFoundException:在DLL中找不到入口点

本文关键字：找不到 入口 DLL EntryNotFoundException System | 更新日期: 2023-09-27 18:24:59

我正在准备一个小的C++dll，其中的函数将从C#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());
        }
    }
}

我得到异常："System.EntryNotFoundException：无法在DLL中找到入口点"

创建新项目时，我使用的是Visual Studio提供的默认模板，Visual C++->Win32项目->DLL（已选中导出符号）。有人能提出解决这个问题的办法吗。我找了很久也没能找到问题。

System.EntryNotFoundException:在DLL中找不到入口点

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（为简便起见，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();
        }
    }
}

可能是您的C#进程以64位运行，而DLL是32位，反之亦然。当进程和DLL的位不匹配时，我看到过这个问题。

看起来您没有定义DLLFUNCTIONEXPOSETEST_EXPORTS，所以您使用导入声明。要进行测试，请使用dumpbin/exports查看从dll导出了哪些函数。

添加

#define DLLFUNCTIONEXPOSETEST_EXPORTS 1 
#include DLLTestFile.h
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