input_test2.rb

require 'io/console'

puts "Angle( C-c: exit )\n1. 0°\n2. 90°\n3. 180°"

while c = STDIN.getch
  exit if c == ?\C-c

  if c == "1" || c == "2" || c == "3"
    print c
    puts "\nAngle( C-c: exit )\n1. 0°\n2. 90°\n3. 180°"
  else
    puts "Prease choose 1-3 number"
  end
end