How to convert a string to lower or upper case in Ruby
RubyStringUppercaseLowercaseRuby Problem Overview
How do I take a string and convert it to lower or upper case in Ruby?
Ruby Solutions
Solution 1 - Ruby
Ruby has a few methods for changing the case of strings. To convert to lowercase, use downcase:
"hello James!".downcase #=> "hello james!"
Similarly, upcase capitalizes every letter and capitalize capitalizes the first letter of the string but lowercases the rest:
"hello James!".upcase #=> "HELLO JAMES!"
"hello James!".capitalize #=> "Hello james!"
"hello James!".titleize #=> "Hello James!" (Rails/ActiveSupport only)
If you want to modify a string in place, you can add an exclamation point to any of those methods:
string = "hello James!"
string.downcase!
string #=> "hello james!"
Refer to the documentation for String for more information.
Solution 2 - Ruby
You can find out all the methods available on a String by opening irb and running:
"MyString".methods.sort
And for a list of the methods available for strings in particular:
"MyString".own_methods.sort
I use this to find out new and interesting things about objects which I might not otherwise have known existed.
Solution 3 - Ruby
Like @endeR mentioned, if internationalization is a concern, the unicode_utils gem is more than adequate.
$ gem install unicode_utils
$ irb
> require 'unicode_utils'
=> true
> UnicodeUtils.downcase("FEN BİLİMLERİ", :tr)
=> "fen bilimleri"
String manipulations in Ruby 2.4 are now unicode-sensitive.
Solution 4 - Ruby
The ruby downcase method returns a string with its uppercase letters replaced by lowercase letters.
"string".downcase
https://ruby-doc.org/core-2.1.0/String.html#method-i-downcase
Solution 5 - Ruby
... and the uppercase is:
"Awesome String".upcase
=> "AWESOME STRING"
Solution 6 - Ruby
The Rails Active Support gem provides upcase, downcase, swapcase,capitalize, etc. methods with internationalization support:
gem install activesupport
irb -ractive_support/core_ext/string
"STRING ÁÂÃÀÇÉÊÍÓÔÕÚ".mb_chars.downcase.to_s
=> "string áâãàçéêíóôõú"
"string áâãàçéêíóôõú".mb_chars.upcase.to_s
=> "STRING ÁÂÃÀÇÉÊÍÓÔÕÚ"
Solution 7 - Ruby
The .swapcase method transforms the uppercase latters in a string to lowercase and the lowercase letters to uppercase.
'TESTING'.swapcase #=> testing
'testing'.swapcase #=> TESTING
Solution 8 - Ruby
You can find strings method like "strings".methods
You can define string as upcase, downcase, titleize.
For Example,
"hii".downcase
"hii".titleize
"hii".upcase
Solution 9 - Ruby
Since Ruby 2.4 there is a built in full Unicode case mapping. Source: https://stackoverflow.com/a/38016153/888294. See Ruby 2.4.0 documentation for details: https://ruby-doc.org/core-2.4.0/String.html#method-i-downcase
Solution 10 - Ruby
Won't work for every, but this just saved me a bunch of time. I just had the problem with a CSV returning "TRUE or "FALSE" so I just added VALUE.to_s.downcase == "true" which will return the boolean true if the value is "TRUE" and false if the value is "FALSE", but will still work for the boolean true and false.
Solution 11 - Ruby
In combination with try method, to support nil value:
'string'.try(:upcase)
'string'.try(:capitalize)
'string'.try(:titleize)