question about PBASIC 2.5 comparative operators' syntax (<, >=, etc)

brad_lightwriters

does anyone know the proper syntax for PBASIC 2.5 for a 'greater than or equal to' statement?· does it matter if there is a space between the > and the =?· does it matter what order the two operators come in?· for example, in my code i have an IF statement with the condition: 'IF variable >= 50'.· i have a feeling that the code is dropping out of this IF statement when the variable gets to 50, not 51 as one would think would happen.· do i need a space between the > and the = or am i totally offbase in my assumption that this is where my error is?·thanks in advance for any help you can offer.·

Newzed

The proper syntax is:

if a>=b then........

or, for less than or equal to:

if a<=b then........

All this can be found in the Help file.

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Sid Weaver
Do you have a Stamp Tester yet?
http://hometown.aol.com/newzed/index.html

·

Jon Williams

Brad,

Perhpas you should post your program instead of a fragment -- that will probably shed some light on the problem you're facing.

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Jon Williams
Applications Engineer, Parallax

brad_lightwriters

this is the subroutine i am running to calculate which pins and chips to activate in a series of external data latches to light a corresponding neon tube.· there are 100 neon tubes in 4 columns.· each column has 4 8-bit latches, where the 25th neon tube in each column is the only one on the 4th latch.· these bottom tubes are not lighting when connected to the stamp, and i feel that it may have something to do with the IF statements dropping out when neon = 25, 50, or 75.·

CBP_Num_Calculator: 'find the chip, board and pin # from the neon #
··· IF Neon = 100 THEN
······ TempNum = 0
······ ELSE
······ IF Neon >= 75 THEN
······ TempNum = Neon - 75
·········· ELSE
·········· IF Neon >= 50 THEN
·········· TempNum = Neon - 50
·············· ELSE
·············· IF Neon >= 25 THEN
·············· TempNum = Neon - 25
·················· ELSE
·················· TempNum = Neon
·············· ENDIF
··········· ENDIF
······· ENDIF
··· ENDIF·· ' End of this Loop
'

---

'This following Loop is again conditioning
' the variable TempNum to extract the corresponding Pin#
'

---

··· IF TempNum = 0 THEN
······ TempNum = TempNum
··· ELSE
····· IF TempNum < = 8 THEN·· 'TempNum minus the number of pins on a chip (8)
········ TempNum = TempNum -1
········ ELSE
········ IF TempNum > 16 THEN
··········· TempNum = TempNum - 17· 'TempNum minus twice the number of pins
··········· ELSE
··········· TempNum = TempNum - 9· 'Just the 8 pins on their own
········ ENDIF
····· ENDIF··· ' End of this loop
· ENDIF
'

---

·· PinNum = TempNum········· ' Final Pin#
·· BoardNum = ( Neon - 1 )/25· ' Find Board# subroutine
'

---

' Find Chip# Subroutine
'

---

··· ChipNum = (Neon-1)/8
··· ChipNum = ChipNum + BoardNum
RETURN····· ' END of CBP#Calculator

i have also been unable to find any documentation of the syntax for the logical (<, >, >=, etc.) operators anywhere in the help guide or the stamp 2p manual.·

Jon Williams

SELECT-CASE is a *better* choice than stacked IF-THEN (I never go more than one nested IF-THEN).· Like this:

· SELECT neon
··· CASE·100
····· tempNum = 0
··· CASE·75 TO 99
····· tempNum = neon - 75
····CASE·50 TO 74
····· tempNum = neon - 50
····CASE·25 TO 49
····· tempNum = neon - 25
··· CASE·ELSE
····· tempNum = neon
· ENDSELECT

There are other methods in PBASIC (you could do some trikery with LOOKDOWN), but this solution, I think, is the most straightforward.

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Jon Williams
Applications Engineer, Parallax

Jon Williams

Hmmm... after looking at my own post·it·occured to me you could do it with one line of code:

· tempNum = neon // 25

That's better, isn't it?· I love the modulus operator!

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Jon Williams
Applications Engineer, Parallax

brad_lightwriters

thanks, i'll try both of those and let you know how things go.