What is the question mark inside this regex doing?

rubyonrails-talk
1

I thought the ? matches zero or one occurrence of a pattern. However in this example:

def show_regexp(string, pattern)

match = pattern.match(string)

if match

“#{match.pre_match}->#{match[0]}<-#{match.post_match}”

else

“no match”

end

end

a = “The moon is made of cheese”

show_regexp(a, /\s.*?\s/) #=> The-> moon <-is made of cheese

What exactly is the ? doing?

2

'John Merlino' via Ruby on Rails: Talk wrote in post #1155178:

I thought the ? matches zero or one occurrence of a pattern. However in this example:

def show_regexp(string, pattern)   match = pattern.match(string)   if match     "#{match.pre_match}->#{match[0]}<-#{match.post_match}"   else     "no match"   end end

a = "The moon is made of cheese" show_regexp(a, /\s.*?\s/) #=> The-> moon <-is made of cheese

What exactly is the ? doing?

*? -- 0 or more, lazy. Matches will be as small as possible.

/\s.*\s/.match(searchText) (not lazy)

/\s.*?\s/.match(searchText) (lazy)

/\s.*\s/ (not lazy) The-> moon is made of <-cheese (1 match)

/\s.*?\s/ (lazy) => The-> moon <-is-> made <-of cheese (2 matches)