Question

This may be a really simple regex but its one of those problems that have proven hard to google.

I have error codes coming back from a third party system. They are supposed to be in the format:

ZZZ##

where Z is Alpha and # is numeric. They are supposed to be 0 padded, but i’m finding that sometimes they come back

ZZZ#

without the 0 padding.

Anyone know how i could add the 0 padding so i can use the string as an index to a hash?

Answer 1

Here’s my take:

def pad str
  number = str.scan(/\d+/).first
  str[number] = "%02d" % number.to_i
  str
end

6.times do |n|
  puts pad "ZZZ#{7 + n}"
end

# >> ZZZ07
# >> ZZZ08
# >> ZZZ09
# >> ZZZ10
# >> ZZZ11
# >> ZZZ12

Reading:

• String#[]=
• Kernel#sprintf and formatting flags.