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Active Forums => QB64 Discussion => Topic started by: hanness on September 16, 2020, 12:26:30 pm

Title: Time zone conversions
Post by: hanness on September 16, 2020, 12:26:30 pm
Timezone conversions

Are there any time functions in QB64 that will help me to determine the time in another time zone?

As an example, if it is 10:00 PM on September 16, 2020, calculate the current time and date in the UK.

NOTE: The tricky part here is that the number of hours difference between the 2 locations varies because they don't both enter and exit daylight saving time on the same dates.
Title: Re: Time zone conversions
Post by: bplus on September 16, 2020, 12:54:34 pm
Try a "time zone" search.

Also might be in @SpriggsySpriggs API apps.
Title: Re: Time zone conversions
Post by: Bert22306 on September 16, 2020, 04:32:05 pm
Quote from: hanness on September 16, 2020, 12:26:30 pm
Timezone conversions
NOTE: The tricky part here is that the number of hours difference between the 2 locations varies because they don't both enter and exit daylight saving time on the same dates.

That's only one tricky part.

Time zones are quite unpredictable. In principle, they depend on longitude. In practice, the demarcations are quite jagged, subject to local policies in each country and sometimes even regions. For example, some states in the US do not use daylight saving time, while even adjacent states do. And, these policies change, over time.

I don't see any other way than to look it up, and to make sure you have up to date info.
Title: Re: Time zone conversions
Post by: luke on September 17, 2020, 12:05:04 pm
Obligatory Tom Scott video:
Title: Re: Time zone conversions
Post by: bplus on September 17, 2020, 12:39:17 pm
Is this why I everything I read last night is marked "New" again here at this forum?

Title: Re: Time zone conversions
Post by: Richard Frost on September 17, 2020, 04:59:43 pm
Some airports have a wall of clocks like this.  As noted above, a simple constant offset
from Greenwich isn't accurate.  Shucks. 

Code: QB64: [Select]
  1. _TITLE "World Clock"
  2. DEFINT A-Z
  3. DIM p$(30), t!(30), t$(30), x(1), y(1)
  4. SCREEN _NEWIMAGE(640, 480, 32)
  5. black& = _RGB32(0, 0, 0)
  6. green& = _RGB32(0, 200, 0)
  7. white& = _RGB32(200, 200, 200)
  8. FOR i = 1 TO 30: READ p$(i), t!(i): NEXT i
  9.  
  10. begin:
  11. t$ = TIME$
  12. h = VAL(MID$(t$, 1, 2)) + 7 '                    GMT = local + 7
  13. m = VAL(MID$(t$, 4, 2))
  14. IF h > 24 THEN h = h - 24
  15. FOR i = 1 TO 30 '                                actual time for each place
  16.     th = h + INT(t!(i))
  17.     z! = ABS(t!(i)) - ABS(INT(t!(i)))
  18.     tm = m + z! * 60 * SGN(t!(i))
  19.     IF tm < 0 THEN tm = tm + 60: th = th - 1
  20.     IF tm > 59 THEN tm = tm - 60: th = th + 1
  21.     IF th < 0 THEN th = th + 24
  22.     IF th > 23 THEN th = th - 24
  23.     th$ = RIGHT$("0" + LTRIM$(STR$(th)), 2)
  24.     tm$ = RIGHT$("0" + LTRIM$(STR$(tm)), 2)
  25.     t$(i) = th$ + tm$
  27. sort:
  28. sorted = 1
  29. FOR i = 1 TO 29
  30.     s = 0
  31.     IF stype = 0 THEN '                          place
  32.         IF p$(i) > p$(i + 1) THEN s = 1
  33.     ELSE '                                       time of day
  34.         IF t$(i) > t$(i + 1) THEN s = 1
  35.     END IF
  36.     IF s THEN
  37.         SWAP p$(i), p$(i + 1) '                  place
  38.         SWAP t!(i), t!(i + 1) '                  zone
  39.         SWAP t$(i), t$(i + 1) '                  time
  40.         sorted = 0
  41.     END IF
  43. IF sorted = 0 THEN GOTO sort
  44. d = 33: p = 0 '                                  distance, place index
  45. FOR yc = 42 TO 402 STEP 90 '                     x center
  46.     FOR xc = 70 TO 570 STEP 100 '                y center
  47.         x1 = xc - d - 18: y1 = yc - d
  48.         x2 = xc + d + 18: y2 = yc + d + 18
  49.         LINE (x1, y1)-(x2, y2), black&, BF '     erase old
  50.         p = p + 1 '                              place index
  51.         _PRINTSTRING (xc - _PRINTWIDTH(p$(p)) \ 2, yc + d + 4), p$(p)
  52.         CIRCLE (xc, yc), d, green&
  53.         IF VAL(LEFT$(t$(p), 2)) < 12 THEN PAINT (xc, yc), green&, green& ' am/pm
  54.         FOR a = 0 TO 360 STEP 30 '               clock tick marks
  55.             x1 = xc + (d - 3) * COS(_D2R(a))
  56.             y1 = yc + (d - 3) * SIN(_D2R(a))
  57.             CIRCLE (x1, y1), 1, white& '         ticks
  58.         NEXT a
  59.         th = VAL(MID$(t$(p), 1, 2)) '            hour
  60.         tm = VAL(MID$(t$(p), 3, 2)) '            minute
  61.         r! = _D2R(tm * 6 - 90) '                 minute hand
  62.         x(0) = xc + (d - 8) * COS(r!)
  63.         y(0) = yc + (d - 8) * SIN(r!)
  64.         r! = _D2R((th + tm / 60) * 30 - 90) '    hour hand
  65.         x(1) = xc + (d - 16) * COS(r!)
  66.         y(1) = yc + (d - 16) * SIN(r!)
  67.         FOR zz = 0 TO 1 '                        draw hands
  68.             FOR zx = -1 TO 1
  69.                 FOR zy = -1 TO 1
  70.                     LINE (xc + zx, yc + zy)-(x(zz), y(zz)), white&
  71.                 NEXT zy
  72.             NEXT zx
  73.         NEXT zz
  74.     NEXT xc
  75. NEXT yc
  76. t$ = LEFT$(TIME$, 5)
  77. LINE (10, 470)-(630, 471), black&, BF '           erase seconds bar at bottom
  79.     x = VAL(RIGHT$(TIME$, 2)) * 10 + 20
  80.     LINE (10, 470)-(x, 471), green&, B '          seconds bar
  81.     i$ = INKEY$
  82.     IF i$ = CHR$(27) THEN SYSTEM '                Esc to quit
  83.     IF i$ = " " THEN stype = 1 - stype '          spacebar changes sort (time or place)
  84. LOOP UNTIL (t$ <> LEFT$(TIME$, 5)) OR (i$ > "")
  85. GOTO begin
  86.  
  87. DATA Amsterdam,1
  88. DATA Beijing,8
  89. DATA Berlin,1
  90. DATA Brasilia,-3
  91. DATA Cairo,2
  92. DATA Chicago,-6
  93. DATA Delhi,5.5
  94. DATA Denver,-7
  95. DATA Detroit,-5
  96. DATA Edmonton,-7
  97. DATA Gander,-3.5
  98. DATA Hawaii,-10
  99. DATA Hong Kong,8
  100. DATA Houston,-6
  101. DATA Istanbul,2
  102. DATA London,0
  103. DATA Los Angeles,-9
  104. DATA Madrid,1
  105. DATA Mexico City,-6
  106. DATA Moscow,3
  107. DATA New York,-5
  108. DATA Paris,1
  109. DATA Perth,8
  110. DATA Phoenix,-8
  111. DATA Rome,1
  112. DATA Seoul,9
  113. DATA Singapore,8
  114. DATA Sydney,10
  115. DATA Tehran,3.5
  116. DATA Tokyo,9
  117.  
  118.  
Title: Re: Time zone conversions
Post by: SpriggsySpriggs on September 17, 2020, 06:31:42 pm
I don't remember if I have something in my API collection but here is a link to a post where I asked a similar question about conversion for time zones and got some help on that. I use it for programs that I make. It could be in my API collection in my NASA one. Anyways, here is the link:
https://www.qb64.org/forum/index.php?topic=2823.msg121099#msg121099 (https://www.qb64.org/forum/index.php?topic=2823.msg121099#msg121099)
Title: Re: Time zone conversions
Post by: bplus on September 17, 2020, 07:17:23 pm
Ah must of been that I was remembering, thanks Spriggsy.

@Richard Frost nice little app!
Title: Re: Time zone conversions
Post by: hanness on September 19, 2020, 10:28:16 pm
Thanks for the help!
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