Padding integers in Ruby

Question

I am interating through |f|

f.print "ITEM", i

ITEM001 ITEM002 .... ITEM044 .... ITEM745

How can I define i so that if i is 1 it will print 001 always making sure there are three digits?

Answer 1

It's called padding:

5.times do |x|
  puts "ITEM%03d" % x
end
# >> ITEM000
# >> ITEM001
# >> ITEM002
# >> ITEM003
# >> ITEM004

Or alternatively

5.times do |x|
  puts "ITEM" + x.to_s.rjust(3, '0')
end

Answer 2

I like to use printf for this kinds of job, it's flexible enough and easy to remember.

5.times do |x|
  printf("ITEM%03d\t", x)
end

#ITEM000 ITEM001 ITEM002 ITEM003 ITEM004