Capitalize all words in sentence string in Ruby

Question

I have created the following code:

def LetterCapitalize(str)
  str = str.split(" ").each {|word| word.capitalize!}
  str = str.join(" ")
  return str
end

This takes in a basic string and capitalizes the first letter of all of the words. It looks kind of awkward to reassign things to str twice. What is wrong with my style here, if anything at all?

Answer 1

• Your function name should be in snake_case, not PascalCase. (Thanks @rui.)
• It seems like it would make more sense to use map than each here.
• Ruby doesn't need explicit return.
• You might even want to extend the base string class.

Here's my rendition:

class String
  def capitalize_words
    this.split.map { |x| x.capitalize }.join(" ")
    # or:     .map(&:capitalize)
  end
end

"this IS a Test".capitalize_words # => "This Is A Test"

Answer 2

Schism's answer touches on the important points: use snake_case, implicit return, and use map rather than modifying the string instances in-place with a bang-method (!).

However, if the string contains many kinds of whitespace - linebreaks, tabs; not just " " - it may not work as intended.

You could consider using gsub in order to maintain any and all original whitespace:

def capitalize_words(string)
  string.gsub(/\S+/, &:capitalize)
end

This will capitalize words separated by any kind of whitespace, and preserve that whitespace in the resulting string.

The regular expression will match 1 or more consecutive non-whitespace characters (i.e. it'll match individual words), which are then passed to an implicit block that calls capitalize on the word, replacing it in the string.

E.g.

input = "here's a STRING with\n\ta newline aNd a tab character"
puts capitalize_words(input)

will print

Here's A String With
    A Newline And A Tab Character

(StackExchange's system seems to replace the tab character with 4 spaces, but run the code yourself, and it'll remain a \t)

As for monkey patching the String class... up to you. I'd consider it for something like this, but I wouldn't do it immediately. The functionality is generic enough that it'd make sense as an addition to String, but, IMO, the real question is whether its usage is wide-spread enough. If the functionality is only used in a few places, then don't start messing with basic classes.