What's the fastest way to check if a word from one string is in another string?

Question

I have a string of words; let\'s call them bad:

bad = \"foo bar baz\"

I can keep this string as a whitespace separated string,

Answer 1

The include? method is what you need. The ruby String specificacion says:

str.include?( string ) -> true or false Returns true if str contains the given string or character.

"hello".include? "lo" -> true

"hello".include? "ol" -> false

"hello".include? ?h -> true

Note that it has O(n) and what you purposed is O(n^2)

Answer 2

Here's one that will check for words and phrases.

 def checkContent(str)
     bad = ["foo", "bar", "this place sucks", "or whatever"]

     # may be best to map and singularize everything as well. 
     # maybe add some regex to catch those pesky, "How i make $69 dollars each second online..."
     # maybe apply some comparison stuff to check for weird characters in those pesky, "How i m4ke $69 $ollars an hour"


     bad_hash = {}
     bad_phrase_hash = {}

     bad.map(&:downcase).each do |word|
         words = word.split().map(&:downcase)
         if words.length > 1
             words.each do |inner|
                if bad_hash.key?(inner)
                    if bad_hash[inner].is_a?(Hash) && !bad_hash[inner].key?(words.length)
                         bad_hash[inner][words.length] = true
                    elsif bad_hash[inner] === 1
                        bad_hash[inner] = {1=>true,words.length => true}
                    end
                else
                    bad_hash[inner] = {words.length => true}
                end
             end
             bad_phrase_hash[word] = true
         else
             bad_hash[word] = 1
         end
     end

     string = str.split().map(&:downcase)
     string.each_with_index do |word,index|
        if bad_hash.key?(word)
            if bad_hash[word].is_a?(Hash)
                if bad_hash[word].key?(1)
                    return false
                else
                    bad_hash[word].keys.sort.each do |length|
                        value = string[index...(index + length)].join(" ")
                        if bad_phrase_hash.key?(value)
                            return false
                        end
                    end
                end
            else
                return false
            end
        end
     end
     return true
  end