C# 调用C++的dll，通过DllImport方式。 from http://www.cnblogs.com/xiaokang088/archive/2011/04/08/2009673.html

C# 调用C++的dll，通过DllImport方式。

以下例子包含以下几种参数传递方式：

传递string、Int、Int数组、结构体、结构体数组。

比较懒，没写注释，呵呵，各位辛苦了。

demo在这里

C++ Dll 如下：

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

BOOL  APIENTRY DllMain( HMODULE  hModule,
                       DWORD   ul_reason_for_call,
                       LPVOID  lpReserved
                     )
{
    switch  (ul_reason_for_call)
    {
    case  DLL_PROCESS_ATTACH:
    case  DLL_THREAD_ATTACH:
    case  DLL_THREAD_DETACH:
    case  DLL_PROCESS_DETACH:
        break ;
    }
    return  TRUE;
}

struct  PersonInfo
{
    int  id;
    wchar_t  name;
};


struct  StudentInfo
{
    int  id;
    wchar_t  name[100];
};


int  Add( int  para1, int  para2)
{
    return  para1+para2;
};

int  TestStruct( struct  PersonInfo* person)
{
    person->id=10;
    return  0;
};

int  TestStructArray( struct   PersonInfo   persons[5] )
{
    persons[0].id=11;
    persons[0].name = L 'a' ;

    persons[1].id=22;
    persons[1].name = L 'b' ;

    persons[2].id=33;
    persons[2].name = L 'c' ;

    persons[3].id=44;
    persons[3].name = L 'd' ;

    persons[4].id=55;
    persons[4].name = L 'e' ;

    return  0;
};

int  TestStructArray2( struct   StudentInfo   students[3] )
{
    students[0].id=11;
    wcscpy(students[0].name,L "aaaaaaa" );

    TCHAR  szMsg[200] = {0};
    _stprintf_s(szMsg, 200, _T( "size of PersonInfo2:%d" ), sizeof (StudentInfo));
    ::OutputDebugString(szMsg);

    students[1].id=22;
    wcscpy(students[1].name,L "bbbb" );

    students[2].id=33;
    wcscpy(students[2].name,L "ccc" );

    return  0;
};




int  TestIntArr( int  tt[5])
{
    tt[0]=0;
    tt[1]=1;
    tt[2]=2;
    tt[3]=3;
    tt[4]=4;

    return  0;
}

int  TestString( LPTSTR  buffer, DWORD  size)
{
    wcscpy_s(buffer,size,L "eststsetwet" );
    return  0;
}

C++ def文件如下：

LIBRARY "Win32Dll"

EXPORTS
     Add
     TestStruct
     TestStructArray
     TestStructArray2
     TestIntArr
     TestString

C# 调用代码如下：

/// <summary>
/// Interaction logic for Window1.xaml
/// </summary>
public  partial class  Window1 : Window
{
    public  Window1()
    {
        InitializeComponent();
        Loaded += new  RoutedEventHandler(button1_Click);
    }

    private  void  button1_Click(object sender, RoutedEventArgs e)
    {
        int  num1 = 0, num2 = 0;
        if  (!string.IsNullOrEmpty(textBox1.Text) && !string.IsNullOrEmpty(textBox2.Text))
        {
            num1 = Convert.ToInt32(textBox1.Text);
            num2 = Convert.ToInt32(textBox2.Text);

            int  ret = DllTest.Add(Convert.ToInt32(textBox1.Text), Convert.ToInt32(textBox2.Text));
            textBlock3.Text = ret.ToString();
        }

        PersonInfo p = new  PersonInfo();
        DllTest.TestStruct(ref p);

        //int dd = p.id;

        int [] intArray = new  int [5];
        DllTest.TestIntArr(intArray);
        Debug.WriteLine(intArray);

        PersonInfo[] ps = new  PersonInfo[5];
        DllTest.TestStructArray(ps);

        int  t = Marshal.SizeOf( new  StudentInfo());
        //  var t = sizeof(PersonInfo2);

        StudentInfo[] ps2 = new  StudentInfo[3];
        DllTest.TestStructArray2(ps2);

        short [] name = ps2[0].name;
        string ret13 = new  string(name.Where(o => o != 0).Select(o => ( char )o).ToArray());

        char [] chars = new  char [100];

        StringBuilder builder = new  StringBuilder(256);
        DllTest.TestString(builder, 256);
    }

}


public  class  DllTest
{
    [DllImport( "Win32Dll.dll" , EntryPoint = "Add" )]
    public  static  extern  Int32 Add( int  a, int  b);

    [DllImport( "Win32Dll.dll" , EntryPoint = "TestStruct" )]
    public  static  extern  Int32 TestStruct(ref PersonInfo person);

    [DllImport( "Win32Dll.dll" , EntryPoint = "TestStructArray" )]
    public  static  extern  Int32 TestStructArray([In, Out]  PersonInfo[] persons);

    [DllImport( "Win32Dll.dll" , EntryPoint = "TestStructArray2" )]
    public  static  extern  Int32 TestStructArray2([In, Out]  StudentInfo[] students);

    [DllImport( "Win32Dll.dll" , EntryPoint = "TestIntArr" )]
    public  static  extern  Int32 TestIntArr([In, Out] int [] intArray);

    [DllImport( "Win32Dll.dll" , EntryPoint = "TestString" )]
    public  static  extern  Int32 TestString([MarshalAs(UnmanagedType.LPTStr)]StringBuilder buffer, Int32 length);
}

[ComVisible( false ), StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
public  struct  PersonInfo
{
    public  int  id;
    public  char  name;
}

[StructLayout(LayoutKind.Sequential)]
public  struct  StudentInfo
{
    public  int  id;

    [MarshalAs(UnmanagedType.ByValArray, SizeConst = 100)]
    public  short [] name;
}