[Solved]How do I use a variable to contain the search pattern in Ruby using the .gsub() method?

Question

I am trying to isolate integers 0..5 on a word boundary and replace that integer with the corresponding english word.

For example, the string '1 11 5 123' becomes 'one 11 five 123' with numbers larger than 5 remaining unchanged.

Thank you in advance for your help!

https://code.sololearn.com/c5p6ypClE8XY/?ref=app

Answer 1

Use "#{var}" to include a variable inside a regexp:

num = ["zero", "one", "two", "three", "four", "five"]
message = "4 + 2 = 6"

(0..5).each do |i|
message.gsub!(/\b#{i}\b/, num[i])
end

puts message
# four + two = 6

You could do the same with just one call to gsub!():

num = ["zero", "one", "two", "three", "four", "five"]
message = "4 + 2 = 6"

message.gsub!(/\b[0-5]\b/) {|x| num[x.to_i]}

puts message
# four + two = 6

Answer 2

Diego thank you that worked well (both ways) I did run into trouble with the single line line solution if I increased the range from 0..5 to 0..20, but the loop worked no mater the range.

That really helped, as I had done a lot of searches and was having difficulty nailing down the proper syntax.

Answer 3

Diego one more question, can the search pattern be in a variable?

string.gsub!(pattern, replacement)

Answer 4

Yes, you can. Just assign your regexps to a variable:

(0..5).each do |i|
pattern = /\b#{i}\b/
message.gsub!(pattern, num[i])
end

And yes, my second approach only works for numbers 0-9. For a larger range it's simpler to use a loop.

Answer 5

Diego Nice, thank you very much 👍