C# 中调用C/C++ DLL

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实例代码见:http://download.csdn.net/source/1172831

本文通过实例代码说明如何在托管的C#代码中调用非托管的Win32 API或者自己用C/C++写的Dll中的函数，以及如何传递输入、输出字符串参数，结构类型参数等问题。

Win32 C/C++ DLL代码如下(最终编译成dll.dll)：

#include "stdafx.h"

#include <stdio.h>

#ifdef _MANAGED

#pragma managed(push, off)

#endif

//简单的函数调用测试

extern "C" __declspec(dllexport) int Test(void)

{

return 34;

}

//输入输出字符串传递测试

extern "C" __declspec(dllexport) int TCharPara(char *in, int len, char *out)

{

memcpy(out, in, len);

return 0;

}

//结构参数传递测试

struct _XY

{

int x;

int y;

};

extern "C" __declspec(dllexport) int TStructPara(struct _XY *xy)

{

xy->x = 5;

xy->y = 5;

return 0;

}

//回调函数测试

typedef void (CALLBACK *CBFunc)(char *);

extern "C" __declspec(dllexport) int TCallback(CBFunc pf, char *out)

{

(*pf)(out);

return 0;

}

#ifdef _MANAGED

#pragma managed(pop)

#endif

调用Win32 C/C++ dll中函数的托管C#代码如下：

using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Data;

using System.Drawing;

using System.Text;

using System.Windows.Forms;

using System.Runtime.InteropServices;

namespace TCallCDll

{

//用于测试结构参数传递，对应Win32 dll中的结构_XY

[StructLayout(LayoutKind.Sequential)]

public struct _XY

{

public int x;

public int y;

};

//Win32 C/C++ dll中的函数TCallback回调此函数

public delegate void OurDllCallBack(String iin);

//user32.dll中的EnumWindows函数回调此函数

public delegate bool SysCallBack(int hwnd, int lParam);

public class TCallCDll{

[DllImport("dll.dll")]

//////////////////////////////////////////////////////////////////////////

//iin: 输入参数

//oout: 输出参数

//////////////////////////////////////////////////////////////////////////

public static extern int TCharPara(String iin, int len, StringBuilder oout);

//测试结构参数传递的函数

[DllImport("dll.dll")]

public static extern int TStructPara(ref _XY xy);

//自己的dll函数回调测试

[DllImport("dll.dll", CharSet = CharSet.Ansi)]

public static extern void TCallback(OurDllCallBack f, String s);

//user32.dll中的函数回调测试

[DllImport("user32.dll")]

public static extern int EnumWindows(SysCallBack x, int y);

}

public partial class callCDllMain : Form

{

public callCDllMain()

{

InitializeComponent();

}

//提供给dll.dll中的TCallback回调的函数

public static void ff(String s)

{

Console.WriteLine(s);

}

//提供给user32.dll中的EnumWindows回调的函数

public static bool Report(int hwnd, int lParam)

{

Console.Write("Window handle is ");

Console.WriteLine(hwnd);

return true;

}

private void Form1_Load(object sender, EventArgs e)

{

StringBuilder a = new StringBuilder(3);

TCallCDll.TCharPara("ABC", 3, a);

this.Text = a.ToString();

_XY xy = new _XY();

TCallCDll.TStructPara(ref xy);

this.Text += "x:" + xy.x + ", y:" + xy.y;

OurDllCallBack fff = new OurDllCallBack(ff);

TCallCDll.TCallback(fff, "This string is output in C&C++ dll call back function set in C# code/n");

SysCallBack cb = new SysCallBack(Report);

TCallCDll.EnumWindows(cb, 0);

}

}

}

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