Support for the Ruby 2.4 series has ended. See here for reference.
Scans STDIN for data matching format. See IO#scanf for details.
See Scanf for details on creating a format string.
You will need to require 'scanf' to use Kernel#scanf.
# File scanf.rb, line 773
def scanf(format, &b) #:doc:
STDIN.scanf(format ,&b)
end