array_1 = Array.new
array_2 = Array.new(5)
array_3 = Array.new(5, "empty")
array_4 = [1, "two", 3, 5.5]
puts array_1, array_2, array_3 ,array_4
puts array_4[2, 2].join(", ")
puts array_4.values_at(0, 1, 3).join(", ")
array_4.unshift(0)
array_4.shift()
array_4.push(100, 200) # add
array_4.pop # remove one
array_4.concat([10, 20, 30])
puts array_4.size().to_s
puts array_4.include?(100).to_s # contains 100?
puts array_4.count(100) # how many 100s
puts array_4.empty?.to_s # is empty?
puts array_4.join(" ,") # convert to string
p array_4 # print out the whole array
array_4.each do |value|
 puts value
end