Check whether a string contains one of multiple substrings

Question

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

Solution 1

Try parens in the expression:

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

Solution 2

[needle1, needle2].any? { |needle| haystack.include? needle }

Solution 3

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.)

Solution 4

(haystack.split & [needle1, needle2]).any?

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

Solution 5

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

needles = ["whatever", "pretty"]

if haystack.match?(Regexp.union(needles))
  ...
end

View more solutions

Comments

[emery]

also works with .all? if you wanted AND logic instead of OR logic. Thanks, seph!

[daybreaker]

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 }

[RobinSH]

Your code has a typo, it should be match no question mark.

[emlai]

@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.

[Wassim Dhif]

Can't believe that was it. Thank you.

[Redoman]

@SephCordovano your comment is confusing. You should either expand it or delete it.

[Seph Cordovano]

@jj_What's confusing about it? If you want to search for an array of substrings you use a union.

[Sgnl]

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.

[Joshua Pinter]

This is a fantastic answer. Clean and scalable.