Collection of extension methods for working DateTime value in .NET.

DateTimeExtensionMethods.cs

public static class DateTimeExtensionMethods
{
 	//get first day of month for a given date
	public static DateTime FirstDayOfMonth(this DateTime input)
	{
		return new DateTime(input.Year, input.Month, 1); 
	}
 
 	//get last day of month for a given date
	public static DateTime LastDayOfMonth(this DateTime input)
	{
		//get first day of NEXT month, subtract one day
		return input.AddMonths(1).FirstDayOfMonth().AddDays(-1);
	}
 
}