Select... Case help (Limiting a variable from 1 to 12)

Zeus · 2011-02-12 08:01

Hello,

I am looking for help using "Select Case" statements. I am building an alarm clock and I want to limit the hour input to a range of 1 - 12 hours. A portion of the code is below.

I am also wondering if there is a good reference for "Select Case" statements. The books that I have only cover the basics and my code frequently requires a slightly more complicated solution.

Thanks... Zeus

'Alarm Hour Buttons Block
IF (MenuNum = 0) THEN

SELECT INA & 3
CASE = 3
AlarmHour = 6
CASE = 2
AlarmHour = AlarmHour + 1 // 13
CASE = 1
AlarmHour = AlarmHour - 1 MAX 12
ENDSELECT

ENDIF

Mike Green · 2011-02-12 08:40

How about starting first with an explanation of what you're trying to do? Sure you want to limit the hour input to 1-12, but where is the hour input coming from and what form does it take? You seem to be using at least an UP / DOWN button, but you need to give a better description of what you've got and how it's supposed to behave.

Zeus · 2011-02-12 08:54

Mike Green wrote: »

How about starting first with an explanation of what you're trying to do? Sure you want to limit the hour input to 1-12, but where is the hour input coming from and what form does it take? You seem to be using at least an UP / DOWN button, but you need to give a better description of what you've got and how it's supposed to behave.

Mike,

I'm afraid there is not much more to tell. I find myself stating this project by writing the button inputs portion first. This is my first program, so unfortunately I do not know where it is going yet. You are correct about the up/down user inputs. Basically I want to limit the logic so that the user is unable to enter a bad value. I have not worked out how this will be used within the rest of the program.

It seems to me that there must be a way to constrain the input with mathematical operators, but I have not had any success at this point with this approach.

Does this help?

Zeus

Tracy Allen · 2011-02-12 10:05

Zeus,
That logic will work if you consider the alarmhour as 0 to 11 instead of 1 to 12.

SELECT INA & 3 
        CASE = 3                                                                ' both buttons pressed
              AlarmHour = 5                       
        CASE = 2                                  
              AlarmHour = AlarmHour + 1 // 12   ' <- needs to be cycle of 12 from 0 to 11
        CASE = 1                              
              AlarmHour = AlarmHour - 1 MAX 11   ' <- similar, when it goes to -1 (65535 to the BS2), becomes 11
ENDSELECT

Later on when you compare alarmHour with a value you read from an RTC, do something like this to adjust to a 1 to 12 cycle:
IF Hour = AlarmHour +1 THEN ....

Zeus · 2011-02-12 11:20

Tracy,

Thanks for helping me out yet again.

I do not fully understand your code but the logic seems to make sense. Perhaps I should have asked this question first... What would be the most efficient way (code size wise) to limit the cycle to 1 to 12?

Zeus

Tracy Allen · 2011-02-12 11:36

The easiest to understand is probably this:

case 2
  alarmHour = alarmHour + 1
  if alarmHour = 13 then alarmHour = 1
case 1
  alarmHour = alarmHour - 1
  if alarmHour = 0 then alarmHour = 12

Zeus · 2011-02-12 13:01

Thank you Tracy,

I will compare this to your previous code and see if I can make sense of that as well.

Thanks again... Zeus

Select... Case help (Limiting a variable from 1 to 12)

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