def show_regexp(a, re)
if a =~ re
"#{$`}<<#{$&}>>#{$'}"
else
"no match"
end
end
a = "this is a test"
show_regexp(a, /\w+/)
show_regexp(a, /\s.*\s/)
show_regexp(a, /\s.*?\s/)
show_regexp(a, /[aeiou]{2,99}/)
show_regexp(a, /mo?o/)