How do I parse date-time strings with various characters as date delimiters?

Question

NOTE - Yes, the question from 2011 that my question is suggested as a dupe of, this one here, has answers I could use, but Zohar's answer below is by far the best of all of them, and possibly takes into consideration advances in C# that did not exist 7 years ago. Thus the question is indeed a dupe, but the best answer is found HERE, not THERE.

I'm reading the EXIF information in digital photographs taken with a camera, and photographs scanned by my scanner, and am finding that while the Canon scanner formats the date with "/", the Fujifilm camera formats them with ":". I need to parse these strings to DateTime, and would like a nifty short way of doing it. I don't know if other makers provide EXIF data with yet different date formats, such as hyphens ("-"), periods (".") or some other delimiter, and how I am supposed to allow for all of them? I know one way to do it (try-catch blocks looking for FormatException), but is there a better way?

By the way, the EXIF standard specifies yyyy:mm:dd, with the colon (:) for delimiter, but as mentioned, my Canon scanner (Canoscan 9000F Mk II) uses the slant (/). Presumably other makers could use a different delimiter.

The camera is providing: "2008:10:06 16:00:07"

For which I can do:

DateTime dt = DateTime.ParseExact(str, "yyyy:MM:dd HH:mm:ss", System.Globalization.CultureInfo.InvariantCulture);

Or try to catch several variants as follows:

try
{
    dt = DateTime.ParseExact(str, "yyyy:MM:dd HH:mm:ss", System.Globalization.CultureInfo.InvariantCulture);
}
catch (FormatException)
{
    try
    {
        dt = DateTime.ParseExact(str, "yyyy/MM/dd HH:mm:ss", System.Globalization.CultureInfo.InvariantCulture);
    }
    catch (FormatException)
    {
        try
        {
            dt = DateTime.ParseExact(str, "yyyy-MM-dd HH:mm:ss", System.Globalization.CultureInfo.InvariantCulture);
        }
        catch (FormatException ex)
        {
            throw ex;
        }

    }
}

Don't get me started on all the rest of the formats that could occur!

Possible duplicate of [Parse string to DateTime in C#](https://stackoverflow.com/questions/5366285/parse-string-to-datetime-in-c-sharp) — crunchy, Apr 04 '18 at 12:37
@crunchy No, that's a very general question about parsing one format. This is about parsing multiple formats. — juharr, Apr 04 '18 at 12:44

Zohar Peled · Accepted Answer · 2018-04-04T13:46:56.870

Be very careful with ambiguous formats. If one device returns yyyy/MM/dd and the other returns yyyy/dd/MM you might find yourself returning wrong results.

I would recommend TryParseExact instead of ParseExact in a try..catch block.

The overload I've linked to can take an array of strings as possible formats, and will parse successfully if the input string matches exactly (at least) one of them.

var formats = new string[] 
{
    "yyyy:MM:dd HH:mm:ss",
    "yyyy/MM/dd HH:mm:ss",
    "yyyy-MM-dd HH:mm:ss"
};

DateTime dt;
if(
   DateTime.TryParseExact(
       str, 
       formats, 
       System.Globalization.CultureInfo.InvariantCulture, 
       DateTimeStyles.AssumeLocal, // Please note AssumeLocal might be wrong here...
       out dt)
 ) // parsed successfully...

How do I parse date-time strings with various characters as date delimiters?

1 Answers1