C# 中字符串转换成日期

拼接字符串的形式

DateTime dateTime=Convert.ToDateTime("20201222".Substring(0,4)+"-"+"20201222".Substring(4,2)+"-"+"20201222".Substring(6,2));

Convert.ToDateTime(string)

Convert.ToDateTime(string) //string格式有要求，必须是yyyy-MM-dd hh:mm:ss

DateTime.ParseExact()

string dateString = "20201222";

DateTime dateTime = DateTime.ParseExact(dateString, "yyyyMMdd", System.Globalization.CultureInfo.CurrentCulture);
//或者

DateTime dateTime = DateTime.ParseExact(dateString, "yyyyMMdd", System.Globalization.CultureInfo.InvariantCulture);

Convert.ToDateTime(string, IFormatProvider)

DateTime dateTime;

DateTimeFormatInfo dtFormat = new System.GlobalizationDateTimeFormatInfo();

dtFormat.ShortDatePattern = "yyyy/MM/dd";

dateTime = Convert.ToDateTime("2012/12/22", dtFormat);

DateTime.TryParse(string,out datetime)

用DateTime.TryParse(string,out datetime)转换后，得到的datetime可以用 datetime.ToString("yyy-MM-dd")来转换为特殊需求的格式