How do I remove the last vowel in a string in Ruby?

Question

How can I define the -last vowel- in a string?

For example, I have a word "classic"

I want to find that the last vowel of the word "classsic" is the letter "i", and delete that last vowel.

I'm thinking :

def vowel(str)
  result = ""
  new = str.split(" ")
  i = new.length - 1
  while i < new.length
    if new[i] == "aeiou"
      new[i].gsub(/aeiou/," ")
    elsif new[i] != "aeiou"
      i = -= 1
    end
  end
  return result
end

Reverse the string, remove the first vowel, then reverse the string back. — Aetherus, Sep 22 '16 at 01:01
You might want to edit your first sentence to remove the reference to Java. — pjs, Sep 22 '16 at 01:35
Another way is `str = "fabulous"; str[str.rindex(/[aeiou]/)] = '' => ""; str #=> "fabulos"`, or `str.dup.tap { |s| s[s.rindex(/[aeiou]/)] = '' }` if `str` is not to be mutated. — Cary Swoveland, Sep 22 '16 at 18:42

score 13 · Answer 1 · answered Sep 22 '16 at 01:37

13

r = /
    .*      # match zero or more of any character, greedily
    \K      # discard everything matched so far
    [aeiou] # match a vowel
    /x      # free-spacing regex definition mode

"wheelie".sub(r,'') #=> "wheeli"
"though".sub(r,'')  #=> "thogh"
"why".sub(r,'')     #=> "why"

answered Sep 22 '16 at 01:37

Cary Swoveland

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That is a much better answer. Beautiful RegEx! – potibas Sep 22 '16 at 01:44
@CarySwoveland: Could you please provide a link, where `\K` is explained? I didn't find this at in the [Ruby Docs for Regexp](https://ruby-doc.org/core-2.2.3/Regexp.html). – user1934428 Sep 22 '16 at 06:25
@user1934428 it's missing from the Ruby documentation, but http://www.regular-expressions.info/keep.html explains it. – Stefan Sep 22 '16 at 06:53
@cary - this is a great explanation! – PartOfTheOhana Dec 04 '18 at 17:53

score 4 · Answer 2 · answered Sep 22 '16 at 01:09

4

Like @aetherus pointed out: reverse the string, remove the first vowel then reverse it back:

str = "classic"
=> "classic"
str.reverse.sub(/[aeiou]/, "").reverse
=> "classc"

answered Sep 22 '16 at 01:09

potibas

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davidhu · Answer 3 · 2016-09-22T02:05:25.797

1

regex = /[aeiou](?=[^aeiou]*\z)/

[aeiou] matches one vowel
[^aeiou]* matches non-vowel characters 0 or more times
\z matches to the end of the string
(?=...) is positive forward looking and not including the match in the final result.

Here are a few examples:

"classic".sub(regex, '') #=> "classc"
  "hello".sub(regex, '') #=> "hell"
  "crypt".sub(regex, '') #=> "crypt

edited Sep 22 '16 at 02:05

answered Sep 22 '16 at 01:47

davidhu

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How do I remove the last vowel in a string in Ruby?

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