C# DateTime.TryParseExact

In some program contexts, you may have a specific format pattern string that you want to parse dates with. The DateTime.TryParseExact method provides a way to specify a format string and use it to convert a string into a DateTime instance. This uses uses the tester-doer pattern.

Example 1

Here we see the DateTime.TryParseExact method in the C# language, which is actually more useful than ParseExact in many programs. It enhances performance and makes your program simpler when you have to deal with lots of invalid date strings.

This C# example program demonstrates the DateTime.TryParseExact method.

Program that uses TryParseExact [C#]

using System;
using System.Globalization;

class Program
{
    static void Main()
    {
	string dateString = "Mon 16 Jun 8:30 AM 2008"; // <-- Valid
	string format = "ddd dd MMM h:mm tt yyyy";
	DateTime dateTime;
	if (DateTime.TryParseExact(dateString, format, CultureInfo.InvariantCulture,
	    DateTimeStyles.None, out dateTime))
	{
	    Console.WriteLine(dateTime);
	}
    }
}

Output

6/16/2008 8:30:00 AM

Note on namespaces used. The InvariantCulture value is found in System.Globalization, so that namespace must be specified. You can see that the TryParseExact method succeeds here.

Example 2

When you need DateTime.TryParseExact, you are usually dealing with invalid formats of dates, or nonexistent dates. Here we see an obviously incorrect date, and DateTime.TryParseExact will return false.

Program 2 that uses TryParseExact [C#]

using System;
using System.Globalization;

class Program
{
    static void Main()
    {
	string dateString = "???";
	string format = "ddd dd MMM h:mm tt yyyy";
	DateTime dateTime;
	if (DateTime.TryParseExact(dateString, format, CultureInfo.InvariantCulture,
	    DateTimeStyles.None, out dateTime))
	{
	    Console.WriteLine(dateTime);
	}
	else
	{
	    Console.WriteLine("Not a date");
	}
    }
}

Output

Not a date

Summary

The DateTime.TryParseExact method receives a formatting string and converts an input string into a DateTime instance. The formatting string must adhere to the standard .NET Framework style; this requirement steepens the learning curve for this method. When possible, it is probably advisable to use TryParse.