• Subject: Re: Can I get the Day of the week?
  • From: boldt@xxxxxxxxxx
  • Date: Wed, 16 May 2001 08:11:47 -0400
  • Importance: Normal

From: "Christopher J. Devous" <cdevous@antigua.com>
Subject: RE: Can I get the Day of the week?
Christopher wrote:
>Try this, it's based on the famous "Doomsday" algorithm by JH Conway:
>    100
>    200       ***
>    300       ***      Program Name --  DOWK
>    400       ***      Description  --  Calculate Day of Week from
>    500       ***                       Date
>    600       ***      Author       --  Christopher J. Devous

As much as I respect John Horton Conway, RPG programmers can't do
day of week computation much shorter than with this procedure:

 // Procedure:  DayOfWeek                                           //
 // Purpose:  Determine the day of week for a particular date       //
 // Parameters:                                                     //
 //    I: dt   -- date                                              //
 // Returns:                                                        //
 //    0..6    -- 0=Sunday, 1=Monday, 2=Tuesday, etc.               //
 // Notes:                                                          //
 //    January 5, 1800 is a Sunday.  This procedure only works for  //
 //    dates later than 1800-01-05.                                 //
P DayOfWeek       b
D DayOfWeek       pi            10i 0
D   dt                            d   value datfmt(*iso)
    return %rem (%diff (dt: d'1800-01-05': *days): 7);
P DayOfWeek       e

Hans Boldt, ILE RPG Development, IBM Toronto Lab, boldt@ca.ibm.com

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