ruby – ` – ‘：nil不能被强制转换为Fixnum(TypeError)

发布时间：2020-12-16 20:48:44 所属栏目：百科来源：网络整理

导读：在我的程序中我得到一个错误,上面写着./ruby_camping.rb：91：in` – ‘：nil无法强制进入Fixnum(TypeError).我想做的是结账我刚刚签到的客人.以下是结账部分的代码块： def self.check_out puts "Welcome to checkout!" puts $camping.current_guests puts

在我的程序中我得到一个错误,上面写着./ruby_camping.rb：91：in` – ‘：nil无法强制进入Fixnum(TypeError).我想做的是结账我刚刚签到的客人.以下是结账部分的代码块：

def self.check_out 
  puts "Welcome to checkout!"
  puts $camping.current_guests
  puts " Here are the current guests,who do you want to checkout?!" 
  puts "State plot number "
  plot = gets.chomp.to_i
  guest = $camping.current_guests[plot-1] 
  puts "State the date for your checkout (a number bigger then " + guest.arrived.to_s + "): "
  # it should not be possible for a guest to checkout before she has checked in
  departureDate = gets.chomp.to_i
  guestStayedDays = departureDate - guest.arrived #Days the guest has stayed
  while (guestStayedDays < 1) do                        
   puts "The date for checkout is not valid. The guest checked in " + guest.arrived.to_s
   puts "Please state a new date."
   departureDate = gets.chomp.to_i
   guestStayedDays = departureDate - guest.arrived
  end       
  guest.departure = departureDate
  guest.plot.increase(guestStayedDays) # increases the electricity meter
  puts guest # prints the guest
  $camping.current_guests[plot-1] = nil # emptys the plot
 end
end

为什么离开日期仍然是零？感谢您的帮助！

解决方法

要获得更详细的答案,您必须指明程序中第91行是哪一行.然而,为了指出你正确的方向,如果你看到nil不能被强制进入Fixnum那么它意味着一个在右边的东西 – 是零.例如

irb(main):001:0> 5 - nil
TypeError: nil can't be coerced into Fixnum
        from (irb):1:in `-'
        from (irb):1

从你的代码我可以看到的唯一可能的例子是guestStayedDays = departureDate – guest.arrived所以我会检查guest.arrived的值.

如果a – 左侧的某些内容为零,例如离开日期或情节然后你会得到未定义的方法’ – ‘为nil：NilClass而不是.

（编辑：李大同）

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