C#调用C/C++ dll

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);
}
}
}