String.equalsIgnoreCase(...) equivalent in Ruby

Question

I want to test 2 strings for equality in Ruby in a case insensitive manner.

In languages, such as Fantom, you simply write:

string1.equalsIgnoreCase(string2)

What's the idiomatic way to do this in Ruby?

SirDarius · Accepted Answer · 2014-01-24T12:15:57.453

16

You can use casecmp

"Test".casecmp("teST")
=> 0

"Test".casecmp("teST2")
=> -1

So to test for equality, you can do:

if str.casecmp(str2).zero?
  # strings are equal
end

edited Jan 24 '14 at 12:15

answered Jan 24 '14 at 11:10

SirDarius

1

You could add `.zero?` at the end. – Michael Kohl Jan 24 '14 at 11:46
I like the addition of `.zero?`, I've not come across that before. – Steve Eynon Jan 24 '14 at 15:26
`Fixnum#nonzero?` and `Fixnum#zero?` are the idiomatic way to avoid using 0 in an if condition which expects true or false, because the 0 value is considered true in that context. – SirDarius Jan 24 '14 at 15:57
3

Surely 'casecmp' suggests that case is important. Shouldn't this have been called 'nocasecmp'? :) – android.weasel Nov 09 '15 at 16:05

score 4 · Answer 2 · answered Jan 24 '14 at 11:09

4

Though there is casecmp:

0 == s1.casecmp(s2) # strings equal

I personally prefer

s1.downcase == s2.downcase

answered Jan 24 '14 at 11:09

1

Your preferred way is not an equivalent, however. :) – Sergio Tulentsev Jan 24 '14 at 12:15
@SergioTulentsev Huh, there are uses of `String#match` suggested around. Compare to those, mine is a stark equivalent :-) – Aleksei Matiushkin Jan 24 '14 at 14:44
I mean the "downcase" approach. It doesn't fit the signature `s1.op(s2)`. Anyway, never mind. :) – Sergio Tulentsev Jan 24 '14 at 15:59
I think the intention of this code is far clearer than the `casecmp` method in the accepted answer. – SDJMcHattie Jul 24 '14 at 09:31
Sure it is and that’s why I do prefer it. – Aleksei Matiushkin Jul 24 '14 at 09:32

score 1 · Answer 3 · answered Jan 24 '14 at 11:08

1

You can convert the strings to lowercase and then compare

a.downcase == b.downcase

Or, if you prefer, to uppercase

a.upcase == b.upcase

answered Jan 24 '14 at 11:08

Zero Fiber

1

While this solution is quite obvious, converting both objects for a simple comparison... just seems a bit over-the-top for me. – Steve Eynon Jan 28 '14 at 11:52

score 1 · Answer 4 · answered Jan 24 '14 at 12:12

1

You can use String#match method :

s = "Test"
s.match(/teST/i) # => #<MatchData "Test">
s.match(/teST2/i) # => nil

Remember in Ruby all objects are has the truth value, except nil and false. So you can use this trick also to perform conditional testing.

answered Jan 24 '14 at 12:12

Arup Rakshit

This solution is by far the most readable and very explicit. But I just don't feel it's the idiomatic `Ruby` way... – Steve Eynon Jan 28 '14 at 11:49
@SteveEynon I use this technique..as it is very basic.. and easy to use. :) – Arup Rakshit Jan 28 '14 at 11:51

4 Answers4