获取程序的根目录

WINFROM:

StreamReader sr = new StreamReader(Application.StartupPath + "\config.txt", Encoding.Default);//获取路径

string cityInfo = sr.ReadToEnd();//读取内容
sr.Close();//关闭流

解释：读取程序的根目录中 名称为config.txt文件的内容

WEBFROM:

 StreamReader sr = new StreamReader(System.AppDomain.CurrentDomain.BaseDirectory + "\config.txt", Encoding.Default);