Converting a String to DateTime

Since you are handling 24-hour based time and you have a comma separating the seconds fraction, I recommend that you specify a custom format:

DateTime myDate = DateTime.ParseExact("2009-05-08 14:40:52,531", "yyyy-MM-dd HH:mm:ss,fff",
                                       System.Globalization.CultureInfo.InvariantCulture);

You have basically two options for this. DateTime.Parse() and DateTime.ParseExact().

The first is very forgiving in terms of syntax and will parse dates in many different formats. It is good for user input which may come in different formats.

ParseExact will allow you to specify the exact format of your date string to use for parsing. It is good to use this if your string is always in the same format. This way, you can easily detect any deviations from the expected data.

You can parse user input like this:

DateTime enteredDate = DateTime.Parse(enteredString);

If you have a specific format for the string, you should use the other method:

DateTime loadedDate = DateTime.ParseExact(loadedString, "d", null);

"d" stands for the short date pattern (see MSDN for more info) and null specifies that the current culture should be used for parsing the string.

try this

DateTime myDate = DateTime.Parse(dateString);

a better way would be this:

DateTime myDate;
if (!DateTime.TryParse(dateString, out myDate))
{
    // handle parse failure
}

Convert.ToDateTime or DateTime.Parse

DateTime.Parse

Syntax:

DateTime.Parse(String value)
DateTime.Parse(String value, IFormatProvider provider)
DateTime.Parse(String value, IFormatProvider provider, DateTypeStyles styles)

Example:

string value = "1 January 2019";
CultureInfo provider = new CultureInfo("en-GB");
DateTime.Parse(value, provider, DateTimeStyles.NoCurrentDateDefault););

• Value: string representation of date and time.
• Provider: object which provides culture specific info.
• Styles: formatting options that customize string parsing for some date and time parsing methods. For instance, AllowWhiteSpaces is a value which helps to ignore all spaces present in string while it parse.

It's also worth remembering DateTime is an object that is stored as number internally in the framework, Format only applies to it when you convert it back to string.

• Parsing converting a string to the internal number type.

• Formatting converting the internal numeric value to a readable string.

I recently had an issue where I was trying to convert a DateTime to pass to Linq what I hadn't realised at the time was format is irrelevant when passing DateTime to a Linq Query.

DateTime SearchDate = DateTime.Parse(searchDate);
applicationsUsages = applicationsUsages.Where(x => DbFunctions.TruncateTime(x.dateApplicationSelected) == SearchDate.Date);

Full DateTime Documentation

I just found an elegant way:

Convert.ChangeType("2020-12-31", typeof(DateTime));

Convert.ChangeType("2020/12/31", typeof(DateTime));

Convert.ChangeType("2020-01-01 16:00:30", typeof(DateTime));

Convert.ChangeType("2020/12/31 16:00:30", typeof(DateTime), System.Globalization.CultureInfo.GetCultureInfo("en-GB"));

Convert.ChangeType("11/شعبان/1437", typeof(DateTime), System.Globalization.CultureInfo.GetCultureInfo("ar-SA"));

Convert.ChangeType("2020-02-11T16:54:51.466+03:00", typeof(DateTime)); // format: "yyyy'-'MM'-'dd'T'HH':'mm':'ss'.'fffzzz"

String now = DateTime.Now.ToString("YYYY-MM-DD HH:MI:SS");//make it datetime
DateTime.Parse(now);

this one gives you

2019-08-17 11:14:49.000

Different cultures in the world write date strings in different ways. For example, in the US 01/20/2008 is January 20th, 2008. In France this will throw an InvalidFormatException. This is because France reads date-times as Day/Month/Year, and in the US it is Month/Day/Year.

Consequently, a string like 20/01/2008 will parse to January 20th, 2008 in France, and then throw an InvalidFormatException in the US.

To determine your current culture settings, you can use System.Globalization.CultureInfo.CurrentCulture.

string dateTime = "01/08/2008 14:50:50.42";  
        DateTime dt = Convert.ToDateTime(dateTime);  
        Console.WriteLine("Year: {0}, Month: {1}, Day: {2}, Hour: {3}, Minute: {4}, Second: {5}, Millisecond: {6}",  
                          dt.Year, dt.Month, dt.Day, dt.Hour, dt.Minute, dt.Second, dt.Millisecond);  

This worked for me:

CultureInfo provider = CultureInfo.InvariantCulture;
DateTime dt = DateTime.ParseExact("2009-05-08 14:40:52,531","yyyy-MM-dd HH:mm:ss,fff", provider);

Do you want it fast?

Let's say you have a date with format yyMMdd.

The fastest way to convert it that I found is:

var d = new DateTime(
(s[0] - '0') * 10 + s[1] - '0' + 2000, 
(s[2] - '0') * 10 + s[3] - '0', 
(s[4] - '0') * 10 + s[5] - '0')

Just, choose the indexes according to your date format of choice. If you need speed probably you don't mind the 'non-generic' way of the function.

This method takes about 10% of the time required by:

var d = DateTime.ParseExact(s, "yyMMdd", System.Globalization.CultureInfo.InvariantCulture);