DST_Calc_v1_00.txt, Calculates U.S. DST Rollovers, Arduino IDE v1.8.12

/*
 DST_Calc_v1_00.txt 24-Aug-2020
 Calculates U.S. (Only) DST Rollovers

 Steps the year from 2014 through 2027 and
 calulates the DST start and stop days of
 the month in March and November respectively.
 The results are displayed in a table which
 can be compared with the table shown on the
 Wikipedia page in Ref.-2 below.

 Note: The DST start/stop equations do not
 take into account 100 year and 400 year Leap
 Year exception rules so they only provide
 valid results from 2007 through 2099.

 Example Output:

 DST_Calc_v1_00.txt 24-Aug-2020
 These dates are valid for the U.S. only.
 See [2] below for U.S. DST exceptions.
 DST dates are valid for 2007 thru 2099[1].
 All DST changes occur on Sunday at 2AM.
 In Mar. add 1-hour, Nov. subtract 1-hour.
 Mnemonic: Spring Forward - Fall Back
 References:
 1. http://delphiforfun.org/programs/math_topics/dstcalc.htm
 2. https://en.wikipedia.org/wiki/Daylight_saving_time_in_the_United_States

 -------------------------------
 Year    DST Start    DST End
 -------------------------------
 2014    March 09    November 02
 2015    March 08    November 01
 2016    March 13    November 06
 2017    March 12    November 05
 2018    March 11    November 04
 2019    March 10    November 03
 2020    March 08    November 01
 2021    March 14    November 07
 2022    March 13    November 06
 2023    March 12    November 05
 2024    March 10    November 03
 2025    March 09    November 02
 2026    March 08    November 01
 -------------------------------
 */

int year, dstStart, dstEnd;
bool run = true;

void setup() {
  Serial.begin(115200);
  Serial.println(); //skip past startup SerMon garbage
  Serial.println(); //ditto

  Serial.println(" DST_Calc_v1_00.txt 24-Aug-2020");
  Serial.println(" These dates are valid for the U.S. only.");
  Serial.println(" See [2] below for U.S. DST exceptions.");
  Serial.println(" DST dates are valid for 2007 thru 2099[1].");
  Serial.println(" All DST changes occur on Sunday at 2AM.");
  Serial.println(" In Mar. add 1-hour, Nov. subtract 1-hour.");
  Serial.println(" Mnemonic: Spring Forward - Fall Back");
  Serial.println(" References:");
  Serial.println(" 1. http://delphiforfun.org/programs/math_topics/dstcalc.htm");
  Serial.println(" 2. https://en.wikipedia.org/wiki/Daylight_saving_time_in_the_United_States");
  Serial.println();

  Serial.println(" -------------------------------");
  Serial.print(" Year    ");
  Serial.print("DST Start    ");
  Serial.println("DST End");
  Serial.println(" -------------------------------");
}

void loop() {
  if(run == true) {
    for(year = 2014; year < 2027; year++) {

      dstStart = 14 - ((1 + ((year * 5) / 4)) % 7);
      dstEnd   =  7 - ((1 + ((year * 5) / 4)) % 7);

      Serial.print(" ");
      Serial.print(year);
      Serial.print("    ");
      Serial.print("March ");
      if(dstStart < 10) {
        Serial.print("0");
      }
      Serial.print(dstStart);
      Serial.print("    ");
      Serial.print("November ");
      if(dstEnd < 10) {
        Serial.print("0");
      }
      Serial.println(dstEnd);

      if(year == 2026) {
        Serial.println(" -------------------------------");
        Serial.println();
        run = false;
      }
    }
  }
}