Ruby Array Select example

ruby_kickstart 2:4

# Write a method named get_squares that takes an array of numbers
# and returns a sorted array containing only the numbers whose square is also in the array
# 
# get_squares [9]                      # => []
# get_squares [9,3]                    # => [3]
# get_squares [9,3,81]                 # => [3, 9]
# get_squares [25, 4, 9, 6, 50, 16, 5] # => [4, 5]

def get_squares(array)
  to_return = array.select do |square|
    square if array.include?(square * square)
  end
  to_return.sort
end

Works, avoid naming things to_return. Try to erase the context. You don't know what array is, you don't know what the method signature means. Does to_return still have any semantics attached? no so much.

Also you need guard conditions. Any publicly facing methods should test for extrema. In this case, test to make sure array.is_a? Array