using System.Runtime.InteropServices;
[DllImport("user32.dll", CallingConvention = CallingConvention.StdCall)]
public static extern int MessageBox(int hWnd, String strMessage, String strCaption, uint uiType);
//调用
MessageBox(0, "您好，这是 PInvoke！", ".net", 0);
原文：http://www.cnblogs.com/xh0626/p/5123404.html