Convert day no. to day name?

Drone

I need to convert a day-of-week number (1-7) to a day-of-week name string (Mon-Sun).

I could write a long conditional statement to do this (IF ELSEIF... perhaps) but

is it possible to use LOOKDOWN (dayNo: "Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun")

to return the day name directly?

If not, what about using LOOKDOWN's returned index number to take multi-character strings out of an array.

Any suggestions appreciated - I'm new to spin.

David

Mike Green

You could use the LOOKDOWN, but the values would have to be STRING("Mon"), etc. which returns the address of the string "Mon".

Spin is a lot like C as far as strings are concerned. They are represented by their addresses and they are stored in byte arrays and zero-terminated.
There are no string variables nor string arrays.

Ariba

I think you have to use LOOKUPZ not LOOKDOWN(Z). Lookdown gives the index in the list.
But you can also define the Stringnames in the DAT section and calculate the pointer. (every name has 3 characters 1 Zero, so the offset is daynumber * 4.

' Version 1
PUB getDayName(n) : stringptr
  stringptr := lookupz(n : String("Mon"),String("Tue"),String("Wed"),String("Thu"),String("Fri"),String("Sat"),String("Sub"))

'Version 2  
PUB getDayName(n) : stringptr
  stringptr := @daynames + n*4
  
DAT
daynames      byte "Mon",0,"Tue",0,"Wed",0,"Thu",0,"Fri",0,"Sat",0,"Sun",0

Chris Savage

Drone,

This sounds like DS1302 (or similar) code…There are several examples (most in the Completed Projects Forum) of using the DS1302 and the LOOKUP command (in PBASIC) to get the day. While this is different than the LOOKUP command on the Propeller you can use it as Ariba describes or you can populate the index values with the addresses of DATA containing the Day Names, comma delimited for printing. Take care.

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Chris Savage
Parallax Tech Support

Drone

Thanks everyone for the great suggestions. Special thanks to Ariba - your example code works quite well. Attached is a short project that uses both of Ariba's methods and outputs day number and converted day name to a serial LCD.

David