Convert Date String to another Date string with different format

Question

I need to convert an string date with format yyyyMMdd to a date string with format MM/dd/yyyy. Which is the best to do it?

I\'m doing this:

Answer 1

string date = "01/08/2008";
DateTime dt = Convert.ToDateTime(date);     //or       
DateTime dt = DateTime.Parse(date, culture, System.Globalization.DateTimeStyles.AssumeLocal); //or       
// create date time 2008-03-09 16:05:07.123
DateTime dt = new DateTime(2008, 3, 9, 16, 5, 7, 123); //or       

Now Format as you like with dt ...

String.Format("{0:y yy yyy yyyy}", dt);  // "8 08 008 2008"   year
String.Format("{0:M MM MMM MMMM}", dt);  // "3 03 Mar March"  month
String.Format("{0:d dd ffffd ffffdd}", dt);  // "9 09 Sun Sunday" day
String.Format("{0:h hh H HH}",     dt);  // "4 04 16 16"      hour 12/24
String.Format("{0:m mm}",          dt);  // "5 05"            minute
String.Format("{0:s ss}",          dt);  // "7 07"            second
String.Format("{0:f ff fff ffff}", dt);  // "1 12 123 1230"   sec.fraction
String.Format("{0:F FF FFF FFFF}", dt);  // "1 12 123 123"    without zeroes
String.Format("{0:t tt}",          dt);  // "P PM"            A.M. or P.M.
String.Format("{0:z zz zzz}",      dt);  // "-6 -06 -06:00"   time zone

Format part from As from www.csharp-examples.net

Answer 2

Your code is in fact the best (of course better using TryParseExact), however looks like your input string is in the correct format (convertible to DateTime), you just want to re-format it, I think using some string method will help. But I would like to use Regex here:

string output = Regex.Replace(input, "^(\\d{4})(\\d{2})(\\d{2})$", "$2/$3/$1");
//E.g
input = "20130920";
output = "09/20/2013";

Answer 3

What you are doing is fine.

Probably you can improve it by using DateTime.TryParseExact and on successful parsing, format the DateTime object in other format.

string dateString = "20130916";
DateTime parsedDateTime;
string formattedDate;
if(DateTime.TryParseExact(dateString, "yyyyMMdd", 
                    CultureInfo.InvariantCulture, 
                    DateTimeStyles.None, 
                    out parsedDateTime))
{
    formattedDate = parsedDateTime.ToString("MM/dd/yyyy");
}
else
{
       Console.WriteLine("Parsing failed");
}

Answer 4

Your way is totally OK.You may try doing this:-

string res = "20130908";
DateTime d = DateTime.ParseExact(res, "yyyyMMdd", CultureInfo.InvariantCulture);
Console.WriteLine(d.ToString("MM/dd/yyyy"));

Just for reference from MSDN:-

The DateTime.ParseExact(String, String, IFormatProvider) method parses the string representation of a date, which must be in the format defined by the format parameter.