Get AM/PM for a date time in lowercase using only a datetime format

Question

I'm to get a custom DateTime format including the AM/PM designator, but I want the "AM" or "PM" to be lowercase without making the rest of of the characters lowercase.

Is this possible using a single format and without using a regex?

Here's what I've got right now:

item.PostedOn.ToString("dddd, MMMM d, yyyy a\\t h:mmtt")

An example of the output right now would be Saturday, January 31, 2009 at 1:34PM

Answer 1

I would personally format it in two parts: the non-am/pm part, and the am/pm part with ToLower:

string formatted = item.PostedOn.ToString("dddd, MMMM d, yyyy a\\t h:mm") +
                   item.PostedOn.ToString("tt").ToLower();

Another option (which I'll investigate in a sec) is to grab the current DateTimeFormatInfo, create a copy, and set the am/pm designators to the lower case version. Then use that format info for the normal formatting. You'd want to cache the DateTimeFormatInfo, obviously...

EDIT: Despite my comment, I've written the caching bit anyway. It probably won't be faster than the code above (as it involves a lock and a dictionary lookup) but it does make the calling code simpler:

string formatted = item.PostedOn.ToString("dddd, MMMM d, yyyy a\\t h:mmtt",
                                          GetLowerCaseInfo());

Here's a complete program to demonstrate:

using System;
using System.Collections.Generic;
using System.Globalization;

public class Test
{
    static void Main()
    {
        Console.WriteLine(DateTime.Now.ToString("dddd, MMMM d, yyyy a\\t h:mmtt",
                                                GetLowerCaseInfo());
    }

    private static readonly Dictionary<DateTimeFormatInfo,DateTimeFormatInfo> cache =
        new Dictionary<DateTimeFormatInfo,DateTimeFormatInfo>();

    private static object cacheLock = new object();

    public static DateTimeFormatInfo GetLowerCaseInfo()
    {
        DateTimeFormatInfo current = CultureInfo.CurrentCulture.DateTimeFormat;
        lock (cacheLock)
        {
            DateTimeFormatInfo ret;
            if (!cache.TryGetValue(current, out ret))
            {
                ret = (DateTimeFormatInfo) current.Clone();
                ret.AMDesignator = ret.AMDesignator.ToLower();
                ret.PMDesignator = ret.PMDesignator.ToLower();
                cache[current] = ret;
            }
            return ret;
        }
    }
}