Talk:Strange plus numbers

From Rosetta Code

Help with Description

Is there an external, more decriptive link for "strange plus numbers"? Can someone help with the description? Thanks. --Paddy3118 (talk) 07:37, 23 February 2021 (UTC)

It seems that strange numbers and strange plus numbers have been coined by CalmoSoft. The web seems to know nothing of them. 498 is a 'strange plus number' because 4+9 is prime and 9+8 is prime. Every sum of adjacent pairs of digits must be prime. --Chunes (talk) 08:13, 23 February 2021 (UTC)
This would seem to exclude all 1-digit numbers from being 'strange plus numbers,' but I'm no expert. --Chunes (talk) 08:16, 23 February 2021 (UTC)
There's something here but the definition is not the same as CalmoSoft's. Curiously, he always misses off the first column of output in his Ring solutions.
Funnily the first answer given was wrong. I don't know Ring, but what happens is quite obvious: when (row-1) % 11 = 0, a newline is printed but not the strange number. It should probably be see nl + str instead of see nl. Bastet (talk) 00:37, 25 February 2021 (UTC)
Hope there's not going to be too many of these - don't want another unixdict.txt situation! --PureFox (talk) 10:17, 23 February 2021 (UTC)
There appears to be a logic error in his code. Think the last bit should be:
<lang ring>if flag = 1
   see " " + str
   row = row + 1
   if row % 10 = 0
      see nl

ok</lang> --PureFox (talk) 10:55, 23 February 2021 (UTC)

@Chunes If the condition is "the sum of two consecutive digits is always prime", then one-digit numbers should be considered strange (it's vacuously true that for all pairs of consecutive digits the sum is prime). In the C solution I added a condition on n<10 to force them to be non-strange, but it's easy to remove. We could change the task to solve the general solution and decide what to do with one-digit numbers (I think it's better to have them strange). Bastet (talk) 13:33, 24 February 2021 (UTC)

Hello PureFox. I changed the code as you suggested (CalmoSoft)

Good, thanks. Incidentally, I was just adding a Go entry to your [Strange numbers] task, when I noticed there was a similar problem with your Ring entry. Same fix again, I think :) --PureFox (talk) 10:14, 25 February 2021 (UTC)