怎样调用API？

[caozping]

在C＃中怎样可以API函数？
有没有API的类什么的？

[wzs_wzs123]

using System.Runtime.InteropServices;
[DllImport("gdi32.dll")]
private static extern int GetPixel (IntPtr hdc , int x1,int y1);[DllImport("gdi32.dll")]
private static extern int SetPixel (IntPtr hdc , int x1,int y1,int color);

[雪狼1234567]

参见如下简单例子：
// Copyright
// Microsoft Corporation
// All rights reserved

// MsgBox.cs

using System;
using System.Runtime.InteropServices;

public class LibWrap
{
// int MessageBox(HWND hWnd, LPCTSTR lpText, LPCTSTR lpCaption, UINT uType);

[ DllImport( "User32.dll", EntryPoint="MessageBox", CharSet=CharSet.Auto )]
public static extern int MsgBox( int hWnd, String text, String caption, uint type );

// this will cause incorrect output in message window

[ DllImport( "User32.dll", EntryPoint="MessageBoxW", CharSet=CharSet.Ansi )]
public static extern int MsgBox2( int hWnd, String text, String caption, uint type );

// this will cause an exception

[ DllImport( "User32.dll", EntryPoint="MessageBox", CharSet=CharSet.Ansi, ExactSpelling=true )]
public static extern int MsgBox3( int hWnd, String text, String caption, uint type );
}

public class MsgBoxSample
{
public static void Main()
{
LibWrap.MsgBox( 0, "Correct text", "MsgBox Sample", 0 );
LibWrap.MsgBox2( 0, "Incorrect text", "MsgBox Sample", 0 );
try
{
LibWrap.MsgBox3( 0, "No such function", "MsgBox Sample", 0 );
}
catch( EntryPointNotFoundException )
{
Console.WriteLine( "EntryPointNotFoundException thrown as expected!" );
}
}

private void Form1_Closing(object sender, System.ComponentModel.CancelEventArgs e)
{
DialogResult r = MessageBox.Show ( "是否关闭窗口！" , "关闭窗口！" , MessageBoxButtons.YesNo , MessageBoxIcon.Question ) ;
if (!(DialogResult.Yes ==r))
{
e.Cancel = true;
}
}
}

[ArLi2003]

download api explorer help u

from: http://zpcity.com/arli

[lihonggen0]

ms-help://MS.VSCC/MS.MSDNVS.2052/vblr7/html/vastmDeclare.htm
ms-help://MS.VSCC/MS.MSDNVS.2052/vbcn7/html/vaconCallingWindowsAPIs.htm

[Poseidon2]

方法各位都说了，我只想提醒一下，请注意数据类型的对应关系，因为你看api的函数声明一般都是基于VB或VC的，一般如下：
如果是字符串指针，在C#中用StringBuilder,用BYTE[]也行;
如果是int或long用int,是指针的话加一个ref或out;
其它的我也不多说了，只要注意到这点后，上网可以找些东东看看，还有是结构也要注意一下。

[newlife2002_313]

MARK