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Zoho Deluge: Calculate start and end of Daylight Savings Time

What?
An article to document how I calculated the start and end dates of when Daylight Savings Time is in effect.

Why?
Admittedly, most of Zoho apps have this built-in but here's some snippets of code in case you need them.

How?
I will use this to amend and refine but here's the snippets for the various DSTs around the world.

US (Except Arizona, Hawaii and US Territories?):
copyraw 
//
// Starts Second Sunday in March at 2:00
v_FirstMonthDate = toTime(zoho.currentdate.toString("yyyy") + "-03-08 02:00:00");
//
// Ends First Sunday in November at 2:00
v_LastMonthDate = toTime(zoho.currentdate.toString("yyyy") + "-11-01 02:00:00");
//
// loop through each day in a week to get the start and end dates
for each v_DayIndex in {0,1,2,3,4,5,6}
{
    v_CheckDateStart = v_FirstMonthDate.addDay(v_DayIndex);
    if(v_CheckDateStart.toString("E")=="Sun")
    {
        v_DST_StartTime = v_CheckDateStart;
    }
    v_CheckDateEnd = v_LastMonthDate.addDay(v_DayIndex);
    if(v_CheckDateEnd.toString("E")=="Sun")
    {
        v_DST_EndTime = v_CheckDateEnd;
    }
}	
info "Start Date (Current Year): " + v_DST_StartTime.toString("EEEE, yyyy-MM-dd HH:mm");
info "End Date (Current Year): " + v_DST_EndTime.toString("EEEE, yyyy-MM-dd HH:mm");
//
// Starts Second Sunday in March at 2:00
v_FirstMonthDate = toTime(zoho.currentdate.addYear(1).toString("yyyy") + "-03-08 02:00:00");
//
// Ends First Sunday in November at 2:00
v_LastMonthDate = toTime(zoho.currentdate.addYear(1).toString("yyyy") + "-11-01 02:00:00");
//
// loop through each day in a week to get the start and end dates
for each v_DayIndex in {0,1,2,3,4,5,6}
{
    v_CheckDateStart = v_FirstMonthDate.addDay(v_DayIndex);
    if(v_CheckDateStart.toString("E")=="Sun")
    {
        v_DST_StartTime = v_CheckDateStart;
    }
    v_CheckDateEnd = v_LastMonthDate.addDay(v_DayIndex);
    if(v_CheckDateEnd.toString("E")=="Sun")
    {
        v_DST_EndTime = v_CheckDateEnd;
    }
}	
info "Start Date (Next Year): " + v_DST_StartTime.toString("EEEE, yyyy-MM-dd HH:mm");
info "End Date (Next Year): " + v_DST_EndTime.toString("EEEE, yyyy-MM-dd HH:mm");
  1.  // 
  2.  // Starts Second Sunday in March at 2:00 
  3.  v_FirstMonthDate = toTime(zoho.currentdate.toString("yyyy") + "-03-08 02:00:00"); 
  4.  // 
  5.  // Ends First Sunday in November at 2:00 
  6.  v_LastMonthDate = toTime(zoho.currentdate.toString("yyyy") + "-11-01 02:00:00"); 
  7.  // 
  8.  // loop through each day in a week to get the start and end dates 
  9.  for each v_DayIndex in {0,1,2,3,4,5,6} 
  10.  { 
  11.      v_CheckDateStart = v_FirstMonthDate.addDay(v_DayIndex); 
  12.      if(v_CheckDateStart.toString("E")=="Sun") 
  13.      { 
  14.          v_DST_StartTime = v_CheckDateStart; 
  15.      } 
  16.      v_CheckDateEnd = v_LastMonthDate.addDay(v_DayIndex); 
  17.      if(v_CheckDateEnd.toString("E")=="Sun") 
  18.      { 
  19.          v_DST_EndTime = v_CheckDateEnd; 
  20.      } 
  21.  } 
  22.  info "Start Date (Current Year): " + v_DST_StartTime.toString("EEEE, yyyy-MM-dd HH:mm"); 
  23.  info "End Date (Current Year): " + v_DST_EndTime.toString("EEEE, yyyy-MM-dd HH:mm"); 
  24.  // 
  25.  // Starts Second Sunday in March at 2:00 
  26.  v_FirstMonthDate = toTime(zoho.currentdate.addYear(1).toString("yyyy") + "-03-08 02:00:00"); 
  27.  // 
  28.  // Ends First Sunday in November at 2:00 
  29.  v_LastMonthDate = toTime(zoho.currentdate.addYear(1).toString("yyyy") + "-11-01 02:00:00"); 
  30.  // 
  31.  // loop through each day in a week to get the start and end dates 
  32.  for each v_DayIndex in {0,1,2,3,4,5,6} 
  33.  { 
  34.      v_CheckDateStart = v_FirstMonthDate.addDay(v_DayIndex); 
  35.      if(v_CheckDateStart.toString("E")=="Sun") 
  36.      { 
  37.          v_DST_StartTime = v_CheckDateStart; 
  38.      } 
  39.      v_CheckDateEnd = v_LastMonthDate.addDay(v_DayIndex); 
  40.      if(v_CheckDateEnd.toString("E")=="Sun") 
  41.      { 
  42.          v_DST_EndTime = v_CheckDateEnd; 
  43.      } 
  44.  } 
  45.  info "Start Date (Next Year): " + v_DST_StartTime.toString("EEEE, yyyy-MM-dd HH:mm"); 
  46.  info "End Date (Next Year): " + v_DST_EndTime.toString("EEEE, yyyy-MM-dd HH:mm"); 
Yields:
copyraw 
Start Date (Current Year): Sunday, 2021-03-14 02:00
End Date (Current Year): Sunday, 2021-11-07 02:00
Start Date (Next Year): Sunday, 2022-03-13 02:00
End Date (Next Year): Sunday, 2022-11-06 02:00
  1.  Start Date (Current Year): Sunday, 2021-03-14 02:00 
  2.  End Date (Current Year): Sunday, 2021-11-07 02:00 
  3.  Start Date (Next Year): Sunday, 2022-03-13 02:00 
  4.  End Date (Next Year): Sunday, 2022-11-06 02:00 

Europe:
copyraw 
//
// Starts Last Sunday in March at 1:00 UTC
v_FromMonthDate1 = toTime(zoho.currentdate.toString("yyyy") + "-04-01 01:00:00");
//
// Ends Last Sunday in October at 1:00 UTC
v_ToMonthDate1 = toTime(zoho.currentdate.toString("yyyy") + "-10-31 01:00:00");
//
// loop through each day in a week to get the start and end dates
for each v_DayIndex in {0,1,2,3,4,5,6}
{
    v_CheckDateStart = v_FromMonthDate1.subDay(v_DayIndex);
    if(v_CheckDateStart.toString("E")=="Sun")
    {
        v_DST_StartTime = v_CheckDateStart;
    }
    v_CheckDateEnd = v_ToMonthDate1.subDay(v_DayIndex);
    if(v_CheckDateEnd.toString("E")=="Sun")
    {
        v_DST_EndTime = v_CheckDateEnd;
    }
}	
//
// output
info "Start Date (Current Year): " + v_DST_StartTime.toString("EEEE, yyyy-MM-dd HH:mm");
info "End Date (Current Year): " + v_DST_EndTime.toString("EEEE, yyyy-MM-dd HH:mm");
//
// *********************************************************
//
// Starts Last Sunday in March at 1:00 UTC
v_FromMonthDate1 = toTime(zoho.currentdate.addYear(1).toString("yyyy") + "-04-01 01:00:00");
//
// Ends Last Sunday in October at 1:00 UTC
v_ToMonthDate1 = toTime(zoho.currentdate.addYear(1).toString("yyyy") + "-10-31 01:00:00");
//
// loop through each day in a week to get the start and end dates
for each v_DayIndex in {0,1,2,3,4,5,6}
{
    v_CheckDateStart = v_FromMonthDate1.subDay(v_DayIndex);
    if(v_CheckDateStart.toString("E")=="Sun")
    {
        v_DST_StartTime = v_CheckDateStart;
    }
    v_CheckDateEnd = v_ToMonthDate1.subDay(v_DayIndex);
    if(v_CheckDateEnd.toString("E")=="Sun")
    {
        v_DST_EndTime = v_CheckDateEnd;
    }
}	
info "Start Date (Next Year): " + v_DST_StartTime.toString("EEEE, yyyy-MM-dd HH:mm");
info "End Date (Next Year): " + v_DST_EndTime.toString("EEEE, yyyy-MM-dd HH:mm");
  1.  // 
  2.  // Starts Last Sunday in March at 1:00 UTC 
  3.  v_FromMonthDate1 = toTime(zoho.currentdate.toString("yyyy") + "-04-01 01:00:00"); 
  4.  // 
  5.  // Ends Last Sunday in October at 1:00 UTC 
  6.  v_ToMonthDate1 = toTime(zoho.currentdate.toString("yyyy") + "-10-31 01:00:00"); 
  7.  // 
  8.  // loop through each day in a week to get the start and end dates 
  9.  for each v_DayIndex in {0,1,2,3,4,5,6} 
  10.  { 
  11.      v_CheckDateStart = v_FromMonthDate1.subDay(v_DayIndex); 
  12.      if(v_CheckDateStart.toString("E")=="Sun") 
  13.      { 
  14.          v_DST_StartTime = v_CheckDateStart; 
  15.      } 
  16.      v_CheckDateEnd = v_ToMonthDate1.subDay(v_DayIndex); 
  17.      if(v_CheckDateEnd.toString("E")=="Sun") 
  18.      { 
  19.          v_DST_EndTime = v_CheckDateEnd; 
  20.      } 
  21.  } 
  22.  // 
  23.  // output 
  24.  info "Start Date (Current Year): " + v_DST_StartTime.toString("EEEE, yyyy-MM-dd HH:mm"); 
  25.  info "End Date (Current Year): " + v_DST_EndTime.toString("EEEE, yyyy-MM-dd HH:mm"); 
  26.  // 
  27.  // ********************************************************* 
  28.  // 
  29.  // Starts Last Sunday in March at 1:00 UTC 
  30.  v_FromMonthDate1 = toTime(zoho.currentdate.addYear(1).toString("yyyy") + "-04-01 01:00:00"); 
  31.  // 
  32.  // Ends Last Sunday in October at 1:00 UTC 
  33.  v_ToMonthDate1 = toTime(zoho.currentdate.addYear(1).toString("yyyy") + "-10-31 01:00:00"); 
  34.  // 
  35.  // loop through each day in a week to get the start and end dates 
  36.  for each v_DayIndex in {0,1,2,3,4,5,6} 
  37.  { 
  38.      v_CheckDateStart = v_FromMonthDate1.subDay(v_DayIndex); 
  39.      if(v_CheckDateStart.toString("E")=="Sun") 
  40.      { 
  41.          v_DST_StartTime = v_CheckDateStart; 
  42.      } 
  43.      v_CheckDateEnd = v_ToMonthDate1.subDay(v_DayIndex); 
  44.      if(v_CheckDateEnd.toString("E")=="Sun") 
  45.      { 
  46.          v_DST_EndTime = v_CheckDateEnd; 
  47.      } 
  48.  } 
  49.  info "Start Date (Next Year): " + v_DST_StartTime.toString("EEEE, yyyy-MM-dd HH:mm"); 
  50.  info "End Date (Next Year): " + v_DST_EndTime.toString("EEEE, yyyy-MM-dd HH:mm"); 
Yields:
copyraw 
Start Date (Current Year): Sunday, 2021-03-28 01:00
End Date (Current Year): Sunday, 2021-10-31 01:00
Start Date (Next Year): Sunday, 2022-03-27 01:00
End Date (Next Year): Sunday, 2022-10-30 01:00
  1.  Start Date (Current Year): Sunday, 2021-03-28 01:00 
  2.  End Date (Current Year): Sunday, 2021-10-31 01:00 
  3.  Start Date (Next Year): Sunday, 2022-03-27 01:00 
  4.  End Date (Next Year): Sunday, 2022-10-30 01:00 

Additional Note(s):
Source(s):
Category: Zoho :: Article: 791