Use DateTime.TryParseExact to format date string and ignore time

Question

I want to parse string date to DateTime but ignoring time. My expected date format is M/d/yyyy which is 3/29/2018 (without leading zero). The thing is string can be with or without time part and time can have different formats that I will not predict.

var inputDateString = "12/31/2017 12:00:00 AM" // false, but I want to parse
var inputDateString = "12/31/2017" // true
DateTime.TryParseExact(inputDateString, "M/d/yyyy", CultureInfo.InvariantCulture, DateTimeStyles.None, out var parsedDate); 

Is there any way to parse date string having only specific date format and ignore time?

Answer 1

There is an overload to TryParseExact that allows you to pass in multiple formats. If you know in advance which formats to expect, you can use this overload:

void Main()
{
    string[] validFormats = {"M/d/yyyy", "M/d/yyyy hh:mm:ss tt"};

    var inputDateString1 = "12/31/2017 12:00:00 AM"; // false, but I want to parse
    var inputDateString2 = "12/31/2017"; // true

    DateTime.TryParseExact(inputDateString1, validFormats, CultureInfo.InvariantCulture, DateTimeStyles.None, out var dt1);
    DateTime.TryParseExact(inputDateString2, validFormats, CultureInfo.InvariantCulture, DateTimeStyles.None, out var dt2);

}

You can then get only the date portion using the Date property.

Answer 2

You could strip the time part from the input string, or parse the full input, using only the .Date part.

var parsedDate = DateTime.MinValue;
var inputDateString = "12/31/2017 12:00:00 AM"; // false, but I want to parse

// option 1: use only the date part
if (DateTime.TryParseExact((inputDateString ?? "").Split(' ')[0] , "M/d/yyyy", 
        CultureInfo.InvariantCulture, DateTimeStyles.None, out parsedDate))
    Console.WriteLine(parsedDate);

// option 2: use the full input, but ignore the time
if (DateTime.TryParseExact(inputDateString, "M/d/yyyy hh:mm:ss tt", 
        CultureInfo.InvariantCulture, DateTimeStyles.None, out parsedDate))
    Console.WriteLine(parsedDate.Date);

Personally, I would go with the first option.

Answer 3

If you always want to only parse the Date portion that can be done by explicitly ensuring the string is only 10 characters in length. This is a somewhat convoluted example but you can strip out what you don't need, you'll get the idea:

var inputDateString = "12/31/2017 12:00:00 AM";
string datePortion = string.Empty;
DateTime dt;

if (inputDateString.Length>10)
{
    // take first 10 characters of inputDateString
    datePortion = inputDateString.Substring(0, Math.Min(inputDateString.Length, 10));
}
else if (inputDateString.Length==10)
{
    // inputDateString is already 10 characters
    datePortion = inputDateString;
}
else
{
    // inputDateString is less than 10 characters, no date found, do nothing.
}

if(!DateTime.TryParse(datePortion, out dt))
{
   // handle error that occurred, 
}
else
{
    // parse was successful, carry on.
}