CODEWITHSUNDEEP
rubyregexstring
Aleksei Matiushkin
Aleksei Matiushkin

Reputation: 121000

String::scan with string argument behave strange

According to documentation, #scan should accept both String and Regexp instances as parameter. But tests show strange behaviour:

▶ cat scantest.rb 
#!/usr/bin/ruby
puts '='*10
puts 'foo'.scan '.'
puts '='*10
puts 'foo'.scan /./
puts '='*10

▶ rb scantest.rb
# ⇒ ==========
# ⇒ ==========
# ⇒ f
# ⇒ o
# ⇒ o
# ⇒ ==========

Inside both pry and irb, it doesn't properly scan for a string as well. What am I doing wrong?

Upvotes: 0

Views: 101

Answers (2)

falsetru
falsetru

Reputation: 369264

With string '.', it scans for literal dots:

'foo'.scan '.'
# => []
'fo.o'.scan '.'
# => ["."]

While with regular expression /./, it matches any characters (except newline):

'foo'.scan /./
# => ["f", "o", "o"]
"foo\nbar".scan /./
# => ["f", "o", "o", "b", "a", "r"]

Upvotes: 2

Rajarshi Das
Rajarshi Das

Reputation: 12330

your scan should have a parameter that match the string you want to scan otherwise it will return empty arrray

My case:

irb(main):039:0> "foo".scan("o")
=> ["o", "o"]

Your case

   'foo'.scan '.'
    # => []

There is no dot. present on the 'foo' string so scan return empty array

Upvotes: 0

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