How to convert a string to lower or upper case in Ruby

Question

How do I take a string and convert it to lower or upper case in Ruby?

Answer 1

You can find strings method like "strings".methods You can define string as upcase, downcase, titleize. For Example,

"hii".downcase
"hii".titleize
"hii".upcase

Answer 2

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

Answer 3

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!"

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.

Answer 4

... and the uppercase is:

"Awesome String".upcase
=> "AWESOME STRING"

Answer 5

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"