59

I've got a long string-variable and want to find out whether it contains one of two substrings.

e.g.

haystack = 'this one is pretty long'
needle1 = 'whatever'
needle2 = 'pretty'

Now I'd need a disjunction like this which doesn't work in Ruby though:

if haystack.include? needle1 || haystack.include? needle2
    puts "needle found within haystack"
end
Hedge
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8 Answers8

104
[needle1, needle2].any? { |needle| haystack.include? needle }
seph
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    also works with .all? if you wanted AND logic instead of OR logic. Thanks, seph! – emery Oct 30 '15 at 02:52
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    this is the better answer if you need to be flexible with the amount of needles. `needles = [obj1, obj2, ..., objN]; needles.any? { |needle| haystack.include? needle }` – daybreaker Jun 27 '16 at 21:57
66

Try parens in the expression:

 haystack.include?(needle1) || haystack.include?(needle2)
danh
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24

You can do a regex match:

haystack.match? /needle1|needle2/

Or if your needles are in an array:

haystack.match? Regexp.union(needles)

(For Ruby < 2.4, use .match without question mark.)

Emil Laine
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  • Your code has a typo, it should be `match` no question mark. – RobinSH Mar 22 '17 at 21:23
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    @SephCordovano How am I using it wrong and how can I correct it? To me it looks exactly the same as the `match?` method documentation example linked above. – Emil Laine Apr 07 '17 at 15:03
  • @SephCordovano your comment is confusing. You should either expand it or delete it. – Redoman Oct 23 '17 at 06:23
  • @jj_What's confusing about it? If you want to search for an array of substrings you use a union. – Seph Cordovano Oct 23 '17 at 06:38
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    Please check your Ruby version before commenting. 2.4.0 has `match?` whereas previous Ruby versions did not have this method. Added a caveat to the answer to help address some of the comments mentioned here. – Sgnl Feb 08 '18 at 22:19
  • This is a fantastic answer. Clean and scalable. – Joshua Pinter Feb 15 '19 at 03:52
10
(haystack.split & [needle1, needle2]).any?

To use comma as separator: split(',')

rgtk
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9

For an array of substrings to search for I'd recommend

needles = ["whatever", "pretty"]

if haystack.match?(Regexp.union(needles))
  ...
end
Darme
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Seph Cordovano
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5

To check if contains at least one of two substrings:

haystack[/whatever|pretty/]

Returns first result found

Kapitula Alexey
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0

I was trying to find simple way to search multiple substrings in an array and end up with below which answers the question as well. I've added the answer as I know many geeks consider other answers and not the accepted one only. 

haystack.select { |str| str.include?(needle1) || str.include?(needle2) }

and if searching partially: 

haystack.select { |str| str.include?('wat') || str.include?('pre') }
Shiko
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0

Use or instead of ||

if haystack.include? needle1 or haystack.include? needle2

or has lower presedence than || , or is "less sticky" if you will :-)

folium
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  • Using "or" instead of "||" is generally considered as a bad idea. No matter it will actually work in that specific case. More info: https://github.com/rubocop/ruby-style-guide#andor- and https://graceful.dev/courses/the-freebies/modules/ruby-language/topic/episode-125-and-or/ – Not Entered Apr 06 '23 at 00:49