C# Time Formatting. Localization to French how do I get the output "5h 45" for 5:45?

Question

I'm attempting to format dates for a French customer.

I need to format Times as shown in the following examples...

06:00 -> 6 h
08:45 -> 8 h 45
10:30 -> 10 h 30
15:00 -> 15 h
17:22 -> 17 h 22
18:00 -> 18 h

I've been able to use Custom Date and Time Formatting. But I seem to be stuck on this notation that the French (Canadian at least) don't show the Minutes if they are zero "00".

Currently I'm using the following format.

myDateTime.ToString("H \h mm")

How can I make it so "mm" only appears when > 00?

I'd like to avoid the use of an extension method or proxy class since I feel this should be built into the framework. Apparently its standard formatting for French times.

My string "H \h mm" is actually coming from a resource file. ie...

myDateTime.ToString(Resources.Strings.CustomTimeFormat);

Answer 1

I have some bad news for you. The framework does not support the format you are looking for. The following code proves this:

using System;
using System.Globalization;

namespace ConsoleApplication1
{
    public class Program
    {
        static void Main(string[] args)
        {
            // FR Canadian
            Console.WriteLine("Displaying for: fr-CA");
            DisplayDatesForCulture("fr-CA");

            Console.WriteLine();
            Console.WriteLine();
            Console.WriteLine();

            // FR French
            Console.WriteLine("Displaying for: fr-FR");
            DisplayDatesForCulture("fr-FR"); 

            Console.WriteLine();
            Console.WriteLine("Press enter to exit.");
            Console.ReadLine();
        }

        static void DisplayDatesForCulture(string culture)
        {
            var ci = CultureInfo.GetCultureInfo(culture);
            var dt = new DateTime(2010, 10, 8, 18, 0, 0);

            foreach (string s in ci.DateTimeFormat.GetAllDateTimePatterns())
                Console.WriteLine(dt.ToString(s));
        }
    }
}

The app displays all supported datetime formats. None of them support the concept of 18:00 ==> 18 h, etc.

Your best option is to write an extension method or similar approach.

Culture sensitive approach: build an extension helper class:

public static class DateHelper
{
    public static string ToLocalizedLongTimeString(this DateTime target)
    {
        return ToLocalizedLongTimeString(target, CultureInfo.CurrentCulture);
    }

    public static string ToLocalizedLongTimeString(this DateTime target, 
        CultureInfo ci)
    {
        // I'm only looking for fr-CA because the OP mentioned this 
        // is specific to fr-CA situations...
        if (ci.Name == "fr-CA")
        {
            if (target.Minute == 0)
            {
                return target.ToString("H' h'");
            }
            else
            {
                return target.ToString("H' h 'mm");
            }
        }
        else
        {
            return target.ToLongTimeString();
        }
    }
}

You can test like so:

var dt = new DateTime(2010, 10, 8, 18, 0, 0);

// this line will return 18 h
Console.WriteLine(dt.ToLocalizedLongTimeString(CultureInfo.GetCultureInfo("fr-CA")));

// this line returns 6:00:00 PM
Console.WriteLine(dt.ToLocalizedLongTimeString());

var dt2 = new DateTime(2010, 10, 8, 18, 45, 0);

// this line will return 18 h 45
Console.WriteLine(dt2.ToLocalizedLongTimeString(CultureInfo.GetCultureInfo("fr-CA")));

// this line returns 6:45:00 PM
Console.WriteLine(dt2.ToLocalizedLongTimeString());

Answer 2

Following on code4life's extension method idea, here's an extension method. =p

public static string ToCanadianTimeString(this DateTime source)
{
    if (source == null)
        throw new ArgumentNullException("source");

    if (source.Minute > 0)
        return String.Format("{0:hh} h {0:mm}", source);

    else
        return String.Format("{0:hh} h", source);
}