如何修改Web.Config里面的值

0、先添加

<add key="MAXNUM" value="6" />

1、读取值

string maxNum = ConfigurationManager.AppSettings["MAXNUM"];

2、保存值

Configuration config = System.Web.Configuration.WebConfigurationManager.OpenWebConfiguration("~");
AppSettingsSection appSettings = config.AppSettings;
appSettings.Settings["MAXNUM"].Value = nCount.ToString();
config.Save();