如何将日期格式从dd-MMM-yyyy更改为yyyy-MM-dd

Question

I can't change date format, I've tried 2 methods but the output is 0001-01-01

Method 1

hf_test.Value = "1-Jul-2013";

DateTime date;
var success = DateTime.TryParseExact(hf_test.Value,
    "dd-MMM-yyyy",
    CultureInfo.InvariantCulture,
    DateTimeStyles.None,
    out date);

    Resopnse.Write(date.ToString("yyyy-MM-dd"));

Method 2

        hf_test.Value = "1-Jul-2013";
        Alert.Show(DateTime.ParseExact(hf_test.Value , "dd-MMM-yyyy", culture).ToString("yyyy-MM-dd"));

Answer 1

Output of 0001-01-01 means that your date coud not be parsed. The reason is that you've used dd instead of d for a string like "1-Jul-2013" .

So use

DateTime date;
bool success = DateTime.TryParseExact(hf_test.Value,
                            "d-MMM-yyyy",
                            CultureInfo.InvariantCulture,
                            DateTimeStyles.None,
                            out date);

Answer 2

You are using the wrong format specifier, your date string is using a single-digit day but you are using the leading 0 format specifier ( dd ). This expects your date string to have the day formatted as 01-31 .

You need to use the non-leading 0 format specifier ( d ) which allows single digit days ie

 d-MMM-yyyy

See Custom Date and Time Format Strings