C# Native and COM Interoperability

C# 调用WIN32 API 要引用 System,Ssytem.Runtim.InteropServices  两个命名空间.

 

Calling into Native Dlls.

using System;
using System.Runtime.InteropServices;
class MsgBoxTest
{
[DllImport("user32.dll")]
static extern int MessageBox (IntPtr hWnd, string text, string caption,int type);

[DllImport("kernel32.dll")]
static extern int GetWindowsDirectory (StringBuilder sb, int maxChars);

public static void Main()
{
        MessageBox (IntPtr.Zero,"Please do not press this again.", "Attention", 0);

        StringBuilder s = new StringBuilder (256);
       GetWindowsDirectory (s, 256);
       Console.WriteLine (s);
}
}

 

If you are unsure how to call a particular Win32 method, you will usually find an example on the Internet if you search for the
method name and DllImport. The site http://www.pinvoke.net is a wiki that aims to document all Win32 signatures.

 

Marshaling Common Types

          marshal的含义:对函数参数和返回值进行打包处理似的不同线程或进程之间能够通过RPC通信,有对象marshal,接口marshal等

[DllImport("...")]
static extern int Foo ( [MarshalAs (UnmanagedType.LPStr)] string s );

 

The UnmanagedType enumeration includes all the Win32 and COM types that the
marshaler understands. In this case, the marshaler was told to translate to LPStr,
which is a null-terminated single-byte ANSI string.

Marshaling Classes and Structs

using System;
using System.Runtime.InteropServices;

[StructLayout(LayoutKind.Sequential)] 
class SystemTime
{
public ushort Year;
public ushort Month;
public ushort DayOfWeek;
public ushort Day;
public ushort Hour;
public ushort Minute;
public ushort Second;
public ushort Milliseconds;
}

 

 

 

 

 

dir

struct  SystemTime
{
public ushort Year;
public ushort Month;
public ushort DayOfWeek;
public ushort Day;
public ushort Hour;
public ushort Minute;
public ushort Second;
public ushort Milliseconds;
}

 

[DllImport("kernel32.dll")]
static extern void GetSystemTime (SystemTime t);
static void Main()
{
SystemTime t = new SystemTime();
GetSystemTime (t);
Console.WriteLine (t.Year);
}