转换前检查字符串是否为日期时间的最佳做法？

Question

What's the best way to do it?

This is how I'll usually do it:

DateTime newDate;

try
{
    newDate = DateTime.Parse(Textbox.Text);
}
catch
{
    //isn't a datetime
    return;
}

//do stuff with the date

But something tells me that that is a bit wrong. Any ideas?

Answer 1

Use the DateTime.TryParse method instead of using your own try/catch blocks.

string text = "10/16/2009";
DateTime result;

if (DateTime.TryParse(text, out result))
{
    // success, result holds converted value
}
else
{
    // failed
}

Answer 2

The best pattern to use for datetime parsing would be this

string DateFormat = "dd/MM/yyyy"; //Or any other format
DateTime dateTime;
bool success = DateTime.TryParseExact(value, DateFormat, 
       CultureInfo.InvariantCulture, 
           DateTimeStyles.None, 
                out dateTime);

Never use DateTime.Parse and even DateTime.TryParse

Answer 3

If you know what the format of the datetime will be, you can also use DateTime..::.TryParseExact Method

The DateTime.TryParse can cause problems when it is used with dates such as 01/03/2009

Is it 01 Mar or 03 Jan?

I would rather recomend that you use something other than a textbox, like a date picker, or validate the textbox so that you have something like dd MMM yyyy. very seldomly would you go wrong with that.

Answer 4

Little addition to previous answers:

DateTime:

public static DateTime Parse(string s)
{
    return DateTimeParse.Parse(s, DateTimeFormatInfo.CurrentInfo, DateTimeStyles.None);
}

public static bool TryParse(string s, out DateTime result)
{
    return DateTimeParse.TryParse(s, DateTimeFormatInfo.CurrentInfo, DateTimeStyles.None, out result);
}

DateTimeParse:

internal static DateTime Parse(string s, DateTimeFormatInfo dtfi, DateTimeStyles styles)
{
    DateTimeResult result = new DateTimeResult();
    result.Init();
    if (!TryParse(s, dtfi, styles, ref result))
    {
        throw GetDateTimeParseException(ref result);
    }
    return result.parsedDate;
}

TryParse is better

References:

Reflector

Answer 5

Try the following:

DateTime todate;
if(!DateTime.TryParse("2009/31/01", todate))
{
//------------conversion failed-------------//
}