Переход между временем ДП/ПП и 24 часами

получение преобразования

Переход от ДП/ПП к 24-часам:

  between 12:00 AM and 12:59 AM, subtract 12 hours:
12:59 AM --> 0059

between 1:00 AM and 12:59 PM, a straight conversion:
10:00 AM --> 1000

between 1:00 PM and 11:59 PM, add 12 hours:
10:59 PM --> 2259

Переход от 24-часов к ДП/ПП :

  between 0000 and 0059, add 12 hours:
0059 --> 12:59 AM

between 0100 and 1159, straight conversion to AM:
0100 --> 1:00 AM

between 1200 and 1259, straight conversion to PM:
1259 --> 12:59 PM

between 1300 and 2359, subtract 12 hours:
1559 --> 3:59 PM