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End of Life Ruby 3.2 has reached end of life and gets no more fixes. Switch to Ruby 4.0 →

instance method

String#upcase!

upcase!(*options) → self or nil

Upcases the characters in self; returns self if any changes were made, nil otherwise:

Example
s = 'Hello World!' # => "Hello World!"
s.upcase!          # => "HELLO WORLD!"
s                  # => "HELLO WORLD!"
s.upcase!          # => nil

The casing may be affected by the given options; see Case Mapping.

Related: String#upcase, String#downcase, String#downcase!.

See also #upcase #upto #unpack1 #valid_encoding? also in 4.1 · 4.0 · 3.4 · 3.3 · 3.1 · 3.0