Lua gmatch store captured groups as an array

Question

I'm rather new to Lua. For each match of gmatch, I would like to put the capture group results into an array.

The idea is so I get all the capture groups for each match, as an array, so I can do operations on this array, e.g. convert each capture group to an int.

How would I change the following, so it prints 3 2 1?

function split_ipv4(str)
    for parts in str:gmatch('(%d%d?%d?)%.(%d%d?%d?)%.(%d%d?%d?)%.(%d%d?%d?), ') do
       print(parts[4])
    end
end

split_ipv4('192.168.0.3, 192.168.0.2, 192.168.0.1')

Changing parts to p1, p2, p3, p4 and printing p4 works, but is there a way of not creating a variable for each group?

score 3 · Answer 1 · answered Apr 26 '21 at 16:05

3

The most simple way is to change parts to p1, p2, p3, p4
But in case of variable-phobia:

function split_ipv4(str)
   for addr in str:gmatch'%d%d?%d?%.%d%d?%d?%.%d%d?%d?%.%d%d?%d?' do
      local parts = {addr:match'(%d+)%.(%d+)%.(%d+)%.(%d+)'}
      print(parts[4])
    end
end

split_ipv4('192.168.0.3, 192.168.0.2, 192.168.0.1')

answered Apr 26 '21 at 16:05

Egor Skriptunoff

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+1. Thanks for the answer. I thought of this idea too, but ig like you said it's not much more better than `p1, p2, p3, p4` for IPv4. It's better in the case of IPv6 I suppose. – simonzack Apr 26 '21 at 16:09
1

IPv6 is not covered by a single Lua pattern. – Egor Skriptunoff Apr 26 '21 at 16:12

Lua gmatch store captured groups as an array

1 Answers1