【说明】
MessageBox("消息内容", "返回值 确定1",MessageBoxButtons.OK,MessageBoxIcon.Question); 
MessageBox("消息内容",, "返回值 确定1 取消2",MessageBoxButtons.OKCancel, MessageBoxIcon.Asterisk);
MessageBox("消息内容", "返回值 终止3 重试4 忽略5",MessageBoxButtons.AbortRetryIgnore, MessageBoxIcon.Error);
MessageBox("消息内容",  "返回值 是6 否7 取消2",MessageBoxButtons.YesNoCancel, MessageBoxIcon.Exclamation);
MessageBox("消息内容",  "返回值 是6 否7",MessageBoxButtons.YesNo, MessageBoxIcon.Hand);
MessageBox("消息内容", "返回值 重试4 取消2",MessageBoxButtons.RetryCancel, MessageBoxIcon.Information);

MessageBoxIcon: 所有图标样式

MessageBoxIcon.Question                                                                                              MessageBoxIcon.Asterisk                                                                                                     MessageBoxIcon.Information                                                                                                      MessageBoxIcon.Error                                                                                                          MessageBoxIcon.Stop                                                                                                            MessageBoxIcon.Hand                                                                                                        MessageBoxIcon.Exclamation                                                                                                      MessageBoxIcon.Warning                                                                                                                        MessageBoxIcon.None

MessageBox函数MessageBox()函数MessageBox是标准的windows Api函数只能在CWnd类的继承类中使用，在C#中使用时，通常用MessageBox的show方法来实现对话框的弹出，命名空间System.Windows.Forms

应用实例：                                                                                                                                                                    DialogResult r1 = MessageBox.Show ( "是否确定？" , "垃圾处理！" , MessageBoxButtons.AbortRetryIgnore , MessageBoxIcon.Question ) ; 
   int ss1=(int)r1 ;
   if ( ss1==3 ){ }
   if ( ss1==4 ){ }
   if ( ss1==5){ }

http://blog.csdn.net/jiangxinyu/article/details/2304114