山东大学软件服务工程——ruby_intro.rb实验代码

# Part 1

def sum arr

  # YOUR CODE HERE

  return 0 if arr.empty?

  s = 0

  arr.each do |i|

    s += i 

  end

  s

end

def max_2_sum arr

  # YOUR CODE HERE

  if arr.size == 0

    return 0

  elsif arr.size == 1

    return arr[0]

  else

    arr = arr.sort

    arr[arr.size-1]+arr[arr.size-2]

  end

end

def sum_to_n? arr, n

  # YOUR CODE HERE

  if arr.size == 0

    return false

  elsif arr.size == 1

    return  false

  else 

    arr.each do |i|

      arr2 = arr.compact

      arr2.delete(i)

      return true if arr2.include?(n-i) == true

    end

    false

  end

end

# Part 2

def hello(name)

  # YOUR CODE HERE

  return "Hello, "+name;

end

def starts_with_consonant? s

  # YOUR CODE HERE

  if s == ''

    return false

  elsif s =~ /^[^a-zA-Z](.*)/

    return false

  elsif s =~ /^[aeiouAEIOU](.*)/

    return false

  else

    return true

  end

end

def binary_multiple_of_4? s

  # YOUR CODE HERE

  if s == ''

    return false

  elsif s =~ /^[01]*$/

    if s.to_i(2) % "100".to_i(2) == 0

      return true

    else

      return false

    end

  return false

  end

end

# Part 3

class BookInStock

# YOUR CODE HERE

  @isbn = nil

  @price = 0.00

  

  def initialize isbn,price

    if isbn == '' || price <= 0

      raise ArgumentError

    end

    @isbn,@price = isbn,price

  end

  

  def isbn

    @isbn

  end

  

  def isbn= isbn 

    if isbn == ''

      raise ArgumentError

    end

    @isbn = isbn

  end

  

  def price

    @price

  end

  

  def price= price

    if price <= 0

      raise ArgumentError

    end

    @price = price

  end

  

  def price_as_string

    "$"+format("%0.2f",price)

  end

end