字符串轉換爲日期型

如:"20100101"轉換成日期型?

"20100101"轉換成int型怎麼轉換??

1、DateTime dt=Convert.ToDateTime("20100101".Substring(0,4)+"-"+"20100101".Substring(4,2)+"-"+"20071107".Substring(6,2)); 
int i=Convert.ToInt32("20100101");

2、Convert.ToDateTime、DateTime.Parse()

3、string str = "20100101";
DateTime dt = DateTime.ParseExact(str, "yyyyMMdd", null);
int i;
int.TryParse(str, out i);