Parsing dates and times from string in many combinations

Question

I need to parse dates and times from strings. The Problem is that the strings can have any possible format. But I also get the format strings.

So i get:

Date = "9/15/2010"
Time = "16:12:45"
DateFormat = "M/dd/yyyy"
TimeFormat = "h:mm:ss"
TimeZone = "+2:00:00"  // +/- and time in TimeFormat

But i have some problems parsing these strings.

I can't parse the time

DateTime.ParseExact("16:12:45","h:mm:ss",null,DateTimeStyles.None);

does not work and causes a FormatException. What is wrong with this call?

If the DateFormat contains slashes, i need to escape them @"M\/dd\/yyyy". Are there any other chars that would need escaping?

Can i parse the whole DateTime in one? Somehting like:

DateTime.ParseExact(Date+' '+Time+' '+TimeZone,DateFormat+' '+TimeFormat+' +'+TimeFormat,null,DateTimeStyles.None);

Answer 1

Create a custom DateTimeFormatInfo and pass that into DateTime.Parse. Like this:

string dateValue = string.Format("{0} {1}", "9/15/2010", "16:12:45");
var customDateTimeFormatInfo = new DateTimeFormatInfo();
customDateTimeFormatInfo.FullDateTimePattern = string.Format("{0} {1}", "M/dd/yyyy", "h:mm:ss");
DateTime dt = DateTime.Parse(dateValue, customDateTimeFormatInfo);

No escaping required and handled your "h:mm:ss" fine with no modification required.

Answer 2

How about this?

var @return = (DateTime?)null;
if (source != null)
{
    source = source.Trim();
    if (source.Length > 0)
    {
        var fs = new string[]
        {
            "d MMMM yyyy h:mm tt",
            "d MMMM yyyy h:mm:ss tt",
            "d MMMM yyyy HH:mm",
            "d MMMM yyyy HH:mm:ss",
            "d MMMM yyyy",
            "d/M/yy h:mm tt",
            "d/M/yy h:mm:ss tt",
            "d/M/yy HH:mm",
            "d/M/yy HH:mm:ss",
            "d/M/yy",
            "d/M/yyyy HH:mm",
            "d/M/yyyy HH:mm:ss",
            "d/M/yyyy h:mm:ss tt",
            "d/M/yyyy",
            "d/M/yyyy h:mm tt",
            "d-MMMM-yy HH:mm",
            "d-MMMM-yyyy h:mm tt",
            "d-MMMM-yyyy h:mm:ss tt",
            "d-MMMM-yyyy HH:mm",
            "d-MMMM-yyyy HH:mm:ss",
            "d-MMMM-yyyy",
            "d-MMM-yy",
            "d-MMM-yy h:mm tt",
            "d-MMM-yy h:mm:ss tt",
            "d-MMM-yy HH:mm",
            "d-MMM-yy HH:mm:ss",
            "d-MMM-yyyy",
            "d-M-yy h:mm tt",
            "d-M-yy h:mm:ss tt",
            "d-M-yy HH:mm",
            "d-M-yy HH:mm:ss",
            "d-M-yy",
            "d-M-yyyy",
            "yyyy/M/d h:mm tt",
            "yyyy/M/d h:mm:ss tt",
            "yyyy/M/d HH:mm",
            "yyyy/M/d HH:mm:ss",
            "yyyy/M/d",
            "yyyy-M-d h:mm tt",
            "yyyy-M-d h:mm:ss tt",
            "yyyy-M-d HH:mm",
            "yyyy-M-d HH:mm:ss",
            "yyyy-M-d",
            "yyyy-MM-ddTHH:mm:ss",
        };
        @return = DateTime.ParseExact(source, fs,
            System.Globalization.CultureInfo.CurrentCulture,
            System.Globalization.DateTimeStyles.None);
    }
}
return @return;

Answer 3

What is wrong with this call?

The "h:mm:ss" format string expects the hours element to be in 12-hour format (h); The hours in your string are in 24-hour format so you need to use H instead:

DateTime.ParseExact("16:12:45", "H:mm:ss", null, DateTimeStyles.None);

Are there any other chars that would need escaping?

Any literal character in your string that clashes with a format specifier will need to be escaped. For example, / is the date separator but \/ means the literal / character; : is the time separator but \: means the literal : character; y is one of the year specifiers but \y is the literal y character.

Can i parse the whole DateTime in one?

Yes.

Answer 4

Do you know which culture the original string belongs to? If you do you can specify a culture specific DateTimeStyle when calling Parse()

DateTime date = DateTime.Parse("<your specific date>", System.Globalization.CultureInfo.GetCultureInfo("<your culture>").DateTimeFormat);