The previous post, Don’t Parse - TryParse, talked about the safe way to attempt parsing of data and check for success.

However, whenever we parse data, we seldom consider localization issues.

For example, here is code that prints the data in 4 different locales:

// Japan
Thread.CurrentThread.CurrentCulture = new CultureInfo("ja-JP");
Console.WriteLine(DateTime.Now);
// Kenya (English)
Thread.CurrentThread.CurrentCulture = new CultureInfo("en-KE");
Console.WriteLine(DateTime.Now);
// German
Thread.CurrentThread.CurrentCulture = new CultureInfo("de-DE");
Console.WriteLine(DateTime.Now);
// USA (English)
Thread.CurrentThread.CurrentCulture = new CultureInfo("en-US");
Console.WriteLine(DateTime.Now);

This code will print the following:

2025/06/16 21:32:29
16/06/2025 21:32:29
16.06.2025 21:32:29
6/16/2025 9:32:29 PM

You can see here that for each of those locales, the date is in a different format, with different separators.

Why is this rellevant?

Because that becomes a problem during parsing.

You need to provide some information to the runtime so that it knows how to parse your dates.

There are three ways to go about it:

Set The Locale For The Application

In this technique, we configure the application or thread locale and then parse our data as usual. The simplest way is by setting the CurrentCulture of the thread. Here, the thread can be from any application - console, class library, web application, etc.

var japanDate = "2025/06/16 21:32:29";
Thread.CurrentThread.CurrentCulture = new CultureInfo("ja-JP");
_ = DateTime.Parse(japanDate);
var kenyaDate = "16/06/2025 21:32:29";
Thread.CurrentThread.CurrentCulture = new CultureInfo("en-KE");
_ = DateTime.Parse(kenyaDate);
var germanyDate = "16.06.2025 21:32:29";
Thread.CurrentThread.CurrentCulture = new CultureInfo("de-DE");
_ = DateTime.Parse(germanyDate);
var usaDate = "6/16/2025 9:32:29 PM";
Thread.CurrentThread.CurrentCulture = new CultureInfo("en-US");
_ = DateTime.Parse(usaDate);

Set The Locale During Parsing

In this technique, we provide the locale information during parsing.

japanDate = "2025/06/16 21:32:29";
_ = DateTime.Parse(japanDate, new CultureInfo("ja-JP"));
kenyaDate = "16/06/2025 21:32:29";
Thread.CurrentThread.CurrentCulture = new CultureInfo("en-KE");
_ = DateTime.Parse(kenyaDate, new CultureInfo("en-KE"));
germanyDate = "16.06.2025 21:32:29";
_ = DateTime.Parse(germanyDate, new CultureInfo("de-DE"));
usaDate = "6/16/2025 9:32:29 PM";
_ = DateTime.Parse(usaDate, new CultureInfo("en-US"));

Provide The Exact Format String For Parsing

In this technique, we provide the format string for parsing (assuming it is known in advance, or can be provided at runtime).

panDate = "2025/06/16 21:32:29";
_ = DateTime.ParseExact(japanDate, "yyyy/MM/dd HH:mm:ss", CultureInfo.InvariantCulture, DateTimeStyles.None);
kenyaDate = "16/06/2025 21:32:29";
_ = DateTime.ParseExact(kenyaDate, "dd/MM/yyyy HH:mm:ss", CultureInfo.InvariantCulture, DateTimeStyles.None);
germanyDate = "16.06.2025 21:32:29";
_ = DateTime.ParseExact(germanyDate, "dd.MM.yyyy HH:mm:ss", CultureInfo.InvariantCulture, DateTimeStyles.None);
usaDate = "6/16/2025 9:32:29 PM";
_ = DateTime.ParseExact(usaDate, "M/d/yyyy h:mm:ss tt", CultureInfo.InvariantCulture, DateTimeStyles.None);

Note in this technique that no culture information is provided for parsing - the format string alone is used to perform the parsing. If there is a mismatch, an exception will be thrown.

This is the most flexible technique.

The DateTime.TryParse method has overloads supporting these techniques.

TLDR

Do not make any assumptions about the format of your data before parsing. Set the locale directly or use the relevant ParseExact method.

The code is in my GitHub

Happy hacking!