VS2017自己用C++写的DLL，用C#调用出错，找不到入口，请各位大佬帮忙看下

独伴丶梨花影 2020-07-08 04:19:29

这是C++的头文件代码：

这是C++的CPP文件代码：

这是C#的代码

环境都是VS2017DE X64

...全文

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独伴丶梨花影 2020-08-15

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引用 2 楼 OrdinaryCoder 的回复:

1.感觉你Vision_API宏好像定义错了
直接这么定义函数吧 extern "C" __declspec(dllexport) int __stdcall add(int x,int y);
2.看看C++工程是否有.def 文件把对外的函数名粘贴进去

引用 6 楼 Null_Link 的回复:

[DllImport("Dll1.dll", EntryPoint = "add1")]

     public static extern int add1(int a,int b);

感谢！

Null_Link 2020-08-14

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[DllImport("Dll1.dll", EntryPoint = "add1")]

     public static extern int add1(int a,int b);

gd6321374 2020-07-08

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天天写这种的，给你个例子


#ifndef CallReader	
#define CallReader			__stdcall
#else
#define	CallReader			__cdecl
#endif

#ifdef	READER
#define ReaderDLL			extern "C"	__declspec(dllexport)
#else
#define	ReaderDLL			extern "C"	__declspec(dllimport)
#endif
ReaderDLL int CallReader ReadAPlus(UCHAR addr, UCHAR block, UCHAR blockCount, UCHAR dataStream[], UCHAR *dataStreamLength, UCHAR maxLen);


ReaderDLL int CallReader ReadAPlus(UCHAR addr, UCHAR block, UCHAR blockCount, UCHAR dataStream[], UCHAR *dataStreamLength, UCHAR maxLen)
{
	int packLength = 0, status = 0, ik = 0;
	UCHAR packBuffer[128] = {0};

	USBHidExitCommunicate();
	for(ik=0; ik<3; ik++)
	{
		status = USBHidInitCommunicate();
		if(status == DEVICE_ERROR_OK)
			break;

		Sleep(10);
	}

	if(ik == 3)
		return DEVICE_ERROR_NO_CONNECT;

	packBuffer[0] = 0;
	packBuffer[1] = blockCount;
	packBuffer[2] = block;

	status = USBCommandPacketDataTransfer(addr, 0, CMD_APLUS_HLRead, packBuffer, 9);
	if(status)
		return status;

	status = USBCommandReceivePacketData(packBuffer, &packLength, sizeof(packBuffer));
	if(status)
		return status;

	int dataLength = (packBuffer[OFFSET_DATALENGTH_H] << 8) + packBuffer[OFFSET_DATALENGTH_L] - 1;
	if(dataLength > maxLen)
		return DEVICE_ERROR_OUT_OF_SIZE;

	if(packBuffer[OFFSET_STATUS] != OFFSET_STATION)
		return packBuffer[OFFSET_STATUS];

	dataStreamLength[0] = dataLength;
	memcpy(dataStream, &packBuffer[OFFSET_DATA_BEGIN + 8], dataStreamLength[0]);

	return DEVICE_ERROR_OK;
}

C# 调用



     [DllImport("ICReader.dll", EntryPoint = "ReadAPlus", CharSet = CharSet.Ansi, CallingConvention = CallingConvention.StdCall)]
     public static extern int ReadAPlus(byte addr, byte block, byte blockCount, ref byte dataStream, ref byte dataStreamLength, byte maxLen);

github_36000833 2020-07-08

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引用 2 楼 OrdinaryCoder 的回复:

... 直接这么定义函数吧 extern "C" __declspec(dllexport) int __stdcall add(int x,int y); ...

+1 c++会对导出函数进行“名字修饰”(name mangling)。比如add1导出可能被修饰成类似"?add1@@YAXHD@Z"之类的名字。因此，你要用extern "C" 来告诉编译器不要mangling。查看导出可以用dumpbin.exe（再VisualStudio命令行下就有）。 dumpbin.exe /EXPORTS Dll1.dll