字符串时间=19851231; 
的DateTime theTime = DateTime.ParseExact（时间，
年月日，
 CultureInfo.InvariantCulture，
 DateTimeStyles.None）; 
 

Possible Duplicate:
how to convert date from yyyyMMdd format to mm-dd-yyyy fomrat

i have string which contains date in yyyyMMdd format . I want to convert that date in to system date format. using ConvertTo.DateTime() method or any other simple method.

string vlaue =19851231 //yyyyMMdd

DateTime dateTime=1985/12/31;

string time = "19851231";
DateTime theTime= DateTime.ParseExact(time,
                                        "yyyyMMdd",
                                        CultureInfo.InvariantCulture,
                                        DateTimeStyles.None);