.net 下对winapi的调用

C＃例子

using System.Runtime.InteropServices;

[DllImport("user32.dll")]
public static extern int SendMessage(IntPtr hWnd,int Msg,int wParam,int lParam);

//此处主要用来让窗口置于最前(SetWindowPos(this.Handle,-1,0,0,0,0,0x4000|0x0001|0x0002);)
[System.Runtime.InteropServices.DllImport("user32.dll")]
public static extern bool SetWindowPos(IntPtr hWnd,
int hWndInsertAfter,
int X,
int Y,
int cx,
int cy,
int uFlags
);

在C#里调用Win32函数有这么几个要点。

第一：名字要与Win32 API的完全一样。

第二：函数除了要有相应的DllImport类修饰外，还要声明成public static extern类型的。

第三：函数的返回值和参数类型要与Win32 API完全一致！

窗口指针 hWnd 可以用 int 也可以用 IntPtr 推荐使用 IntPtr

VBaisc例子

方法一。

<DllImport("user32.dll")> _
Public Shared Function SetWindowPos(ByVal hWnd As IntPtr, ByVal hWndInsertAfter As Integer, ByVal X As Integer, ByVal Y As Integer, ByVal cx As Integer, ByVal cy As Integer, ByVal uFlags As Integer) As Boolean
End Function

<DllImport("KERNEL32.DLL", EntryPoint:="MoveFileW", SetLastError:=True, _
CharSet:=CharSet.Unicode, ExactSpelling:=True, _
CallingConvention:=CallingConvention.StdCall)> _
Public Shared Function MoveFile(ByVal src As String, ByVal dst As String) As Boolean
' This function copies a file from the path src to the path dst.
' Leave function empty - DLLImport attribute forces calls
' to MoveFile to be forwarded to MoveFileW in KERNEL32.DLL.
End Function

方法二

Declare Function GetUserName Lib "advapi32.dll" Alias _
"GetUserNameA" (ByVal lpBuffer As String, ByRef nSize As Integer) As Integer

详细例子可见另一篇文章

VB.NET编程中调用Windows API
本文来自: 中国网管联盟(bitsCN.com) 详细出处参考：http://www.bitscn.com/dotnet/vb/200605/24574.html

VB.Net查看文件中图标的函数及申明Windows API的方法
本文来自: 中国网管联盟(bitsCN.com) 详细出处参考：http://www.bitscn.com/dotnet/vb/200605/24574.html

附1常用Win32数据类型与.NET平台数据类型的对应表

Figure 2 Non-Pointer Data Types

Win32 Types Specification CLR Type

char, INT8, SBYTE, CHAR	8-bit signed integer	System.SByte
short, short int, INT16, SHORT	16-bit signed integer	System.Int16
int, long, long int, INT32, LONG32, BOOL, INT	32-bit signed integer	System.Int32
__int64, INT64, LONGLONG	64-bit signed integer	System.Int64
unsigned char, UINT8, UCHAR, BYTE	8-bit unsigned integer	System.Byte
unsigned short, UINT16, USHORT, WORD, ATOM, WCHAR, __wchar_t	16-bit unsigned integer	System.UInt16
unsigned, unsigned int, UINT32, ULONG32, DWORD32, ULONG, DWORD, UINT	32-bit unsigned integer	System.UInt32
unsigned __int64, UINT64, DWORDLONG, ULONGLONG	64-bit unsigned integer	System.UInt64
float, FLOAT	Single-precision floating point	System.Single
double, long double, DOUBLE	Double-precision floating point	System.Double
In Win32 this type is an integer with a specially assigned meaning; in contrast, the CLR provides a specific type devoted to this meaning.

附2。net封装的api函数见《 Microsoft Win32 to Microsoft .NET Framework API Map》

附3。一个第三方的api声明程序（未验证过）

http://www.mndsoft.com/downfiles/APIBible.rar