Get the previous month s first and last day dates in c

Question

I can t think of an easy one or two liner that would get the previous months first day and last day   I am LINQ-ifying a survey web app  and they squeezed a new requirement in   The survey must include all of the service requests for the previous month   So if it is April 15th  I need all of Marches request ids   var RequestIds    from r in rdc request                    where r dteCreated  gt   LastMonthsFirstDate  amp  amp                     r dteCreated  lt   LastMonthsLastDate                    select r intRequestId     I just can t think of the dates easily without a switch   Unless I m blind and overlooking an internal method of doing it

User · Answer

DateTime now   DateTime Now  int prevMonth   now AddMonths -1  Month  int year   now AddMonths -1  Year  int daysInPrevMonth   DateTime DaysInMonth year  prevMonth   DateTime firstDayPrevMonth   new DateTime year  prevMonth  1   DateTime lastDayPrevMonth   new DateTime year  prevMonth  daysInPrevMonth   Console WriteLine   0   1    firstDayPrevMonth ToShortDateString      lastDayPrevMonth ToShortDateString

User · Answer

I use this simple one-liner   public static DateTime GetLastDayOfPreviousMonth this DateTime date        return date AddDays -date Day       Be aware  that it retains the time

User · Answer

The way I ve done this in the past is first get the first day of this month  dFirstDayOfThisMonth   DateTime Today AddDays  -   DateTime Today Day - 1        Then subtract a day to get end of last month  dLastDayOfLastMonth   dFirstDayOfThisMonth AddDays  -1     Then subtract a month to get first day of previous month  dFirstDayOfLastMonth   dFirstDayOfThisMonth AddMonths -1

User · Answer

This is a take on Mike W s answer   internal static DateTime GetPreviousMonth bool returnLastDayOfMonth        DateTime firstDayOfThisMonth   DateTime Today AddDays  -   DateTime Today Day - 1          DateTime lastDayOfLastMonth   firstDayOfThisMonth AddDays  -1       if  returnLastDayOfMonth  return lastDayOfLastMonth      return firstDayOfThisMonth AddMonths -1       You can call it like so   dateTimePickerFrom Value   GetPreviousMonth false   dateTimePickerTo Value   GetPreviousMonth true

User · Answer

An approach using extension methods   class Program       static void Main string   args                DateTime t   DateTime Now           DateTime p   t PreviousMonthFirstDay            Console WriteLine  p ToShortDateString               p   t PreviousMonthLastDay            Console WriteLine  p ToShortDateString                Console ReadKey              public static class Helpers       public static DateTime PreviousMonthFirstDay  this DateTime currentDate                 DateTime d   currentDate PreviousMonthLastDay             return new DateTime  d Year  d Month  1               public static DateTime PreviousMonthLastDay  this DateTime currentDate                 return new DateTime  currentDate Year  currentDate Month  1   AddDays  -1              See this link http   www codeplex com fluentdatetime for some inspired DateTime extensions

User · Answer

using Fluent DateTime https   github com FluentDateTime FluentDateTime          var lastMonth   1 Months   Ago   Date          var firstDayOfMonth   lastMonth FirstDayOfMonth            var lastDayOfMonth   lastMonth LastDayOfMonth

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If there s any chance that your datetimes aren t strict calendar dates  you should consider using enddate exclusion comparisons    This will prevent you from missing any requests created during the date of Jan 31   DateTime now   DateTime Now  DateTime thisMonth   new DateTime now Year  now Month  1   DateTime lastMonth   thisMonth AddMonths -1    var RequestIds   rdc request    Where r   gt  lastMonth  lt   r dteCreated     Where r   gt  r dteCreated  lt  thisMonth     Select r   gt  r intRequestId

User · Answer

DateTime LastMonthLastDate   DateTime Today AddDays 0 - DateTime Today Day   DateTime LastMonthFirstDate   LastMonthLastDate AddDays 1 - LastMonthLastDate Day

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The canonical use case in e-commerce is credit card expiration dates  MM yy  Subtract one second instead of one day  Otherwise the card will appear expired for the entire last day of the expiration month   DateTime expiration   DateTime Parse  07 2013    DateTime endOfTheMonthExpiration   new DateTime    expiration Year  expiration Month  1  AddMonths 1  AddSeconds -1

User · Answer

var today   DateTime Today  var month   new DateTime today Year  today Month  1          var first   month AddMonths -1   var last   month AddDays -1     In-line them if you really need one or two lines

[c#] Get the previous month's first and last day dates in c#

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