Ruby正则表达式提取字符串中不包含空格的单词

Question

Say I have the string str = "ASimpleNoSpaceTitle" . I can't seem to wrap my head around how to use regexp to split and extract all the capitalized words so that I get ["A", "Simple", "No", "Space", "Title"] .

What's a regular expression that will do the job?

UPDATE: What about a string of words with and without spaces/upper-case? Like "ASimpleNoSpaceTitle and a subtitle" to ["A", "Simple", "No", "Space", "Title", "and", "a", "subtitle"]

Answer 1

Using String#scan with character class ranges will get you what you want with a simple, easy-to-understand regex:

str = "ASimpleNoSpaceTitle"
str.scan(/[A-Z][a-z]*/) # => ["A", "Simple", "No", "Space", "Title"]

You could use the POSIX bracket expressions [[:upper:]] and [[:lower:]] , which would allow your regex to also deal with non-ASCII letters such as À or ç:

str = "ÀSimpleNoSpaçeTitle"
str.scan(/[A-Z][a-z]*/) # => ["Simple", "No", "Spa", "Title"]
str.scan(/[[:upper:]][[:lower:]]*/) # => ["À", "Simple", "No", "Spaçe", "Title"]

To allow words to begin with a lowercase letter when not preceded by another letter, you can use this varuation:

str = "ASimpleNoSpaceTitle and a subtitle"
str.scan(/[A-Za-z][a-z]*/) # => ["A", "Simple", "No", "Space", "Title", "and", "a", "subtitle"]
# OR
str.scan(/[[:alpha:]][[:lower:]]*/)

Answer 2

"ABSimpleNoSpaceTitle".split(/(?=[[:upper:]])/)
  #=> ["A", "B", "Simple", "No", "Space", "Title"]

(?=[[:upper:]]) in a positive lookahead, requiring the match to be followed by a capital letter.

Answer 3

The correct way to do this in 2016 is:

"ASimpleNoSpaceTitle and a subtitle".split(/(?=\p{Lu})|\s+/)
#⇒ ["A","Simple","No","Space","Title","and","a","subtitle"]

Answer 4

Here is one way to do it.

pass this regex inside the built in scan() method.

regext /[[:upper:]](?:[[:lower:]]+)?/

All the regex does is find an upper case letter [[:upper:]] that is optionally followed by a lower case letter (?:[[:lower:]]+)? .

scan will look for more than one occurrence of the match string/char..etc

irb(main):001:0> str = "ASimpleNoSpaceTitle"
=> "ASimpleNoSpaceTitle"

irb(main):050:0> str.scan(/[[:upper:]](?:[[:lower:]]+)?/)
=> ["A", "Simple", "No", "Space", "Title"]
irb(main):051:0>