C# yyyyMMddHHmmss转yyyy-MM-dd HH:mm:ss

string temp_time = "20091225091010";
DateTime dateTime = DateTime.ParseExact(temp_time, "yyyyMMddHHmmss", CultureInfo.CurrentCulture, DateTimeStyles.None);

string temp_time = "20091225091010";
string results = DateTime.ParseExact(temp_time, "yyyyMMddHHmmss", null).ToString("yyyy-MM-dd HH:mm:ss");

string src = "2009-12-25 09:10:10";
string result = DateTime.ParseExact(src, "yyyy-MM-dd HH:mm:ss", null).ToString("yyyyMMddHHmmss");