rubystringbyebug

Why does include? for Ruby return false?

I have the following Ruby fragment from a byebug session:

(byebug) target_name
"foo/"
(byebug) target_name.class
String
(byebug) target_name.include?('/')
false
(byebug) "foo/".include?('/')
true

Why does the include? method return false as / is part of foo/?

Ruby version:

ruby 2.6.1p33 (2019-01-30 revision 66950) [x86_64-linux]
Solution

  • It is possible that target_string contains some non-ascii characters.

    For example compare:

    irb(main):019:0>> str = "foo/"
=> "foo/"
irb(main):020:0> str.ascii_only?
=> true
irb(main):021:0> str.include?("/")
=> true

    and

    irb(main):022:0> str = "foo\xe2\x88\x95"
=> "foo∕"
irb(main):023:0> str.ascii_only?
=> false
irb(main):024:0> str.include?("/")
=> false

    In the latter example the string contains the "forward slash" U+2215 character encoded as utf-8 bytes.

    Depending on your specific use case, you could e.g. convert the string to ascii and blindly replace any undefined or invalid character with a /.

    str.encode("ascii", "utf-8", replace: "/")

    Look at the #encode method for more options.