Question

I was looking on how to have a leading zero in ruby, and I found out the solution: use %02d”
Now, I’d like to do a loop, and keep this zero !
When I do something like this

i = "%02d" % "1".to_i
until (i == 10)
  puts i
  i += 1
end

I have an error “Cannot convert FixNum to string”.
So I decide to do this

i = "%02d" % "1".to_i
"01"
until (i == 10)
  puts i
  i = i.to_i
  i += 1
end

So, this time, the loop work, but only the first number have the leading 0.
I ran out of idea, so I’d appreciate a little help !

Answer 1

I’m not a Ruby developer, but fundamentally I think you need to separate out the idea of the number i, and the text representation with a leading 0. So something like:

for i in (1..10)
  puts "%02d" % i
end

(As you can see from the other answers, there are plenty of ways of coding the loop itself.)

Here i is always a number, but the expression "%02d" % i formats i as a two-digit number, just for display purposes.