Ruby：编写一个一直运行到资源耗尽的循环程序？答案

【问题标题】：Ruby: Writing a Looping Program that Runs until resources are exhausted?Ruby：编写一个一直运行到资源耗尽的循环程序？
【发布时间】：2018-06-15 17:55:52
【问题描述】：

我正在尝试用 Ruby 编写一个程序，该程序将评估一个人可以用多少瓶盖换取额外的苏打水，以及他们可以坚持多久，直到他们不能再换我很难想象这是如何工作的。但这是我目前所拥有的。

规则：

User currently has 10 bottlecaps
They can trade in 3 bottlecaps to get a soda
User trades in 9/10 bottlecaps to get 3 extra sodas
Now they have 4 bottlecaps (1 left over and the 3 that were traded in)
They can trade in 3 more bottlecaps to get one extra soda
Now they have 1 bottlecap, and cannot trade in anymore

这是我目前所拥有的

bottlecaps = 10
for_trade = 3
traded_sodas = bottlecaps / for_trade
num_bottlecaps_traded = for_trade * traded_sodas
bottlecaps = bottlecaps - num_bottlecaps_traded

但我需要弄清楚如何让它循环，直到用户不能再交易瓶盖。谁能指点一下？

【问题讨论】：

标签： ruby loops for-loop while-loop

【解决方案1】：

Ruby 可以像这样永远循环

loop do
  # code in here runs over and over again
end

要停止循环，您可以使用 break 关键字并检查是否有一些条件表明循环应该结束，在您的情况下

loop do
  break if bottlecaps < for_trade
  # trade bottlecaps...
end

编写这种循环的更简洁的方法是使用until

until bottlecaps < for_trade
  # trade bottlecaps
end

或者如果你喜欢更积极地思考

while bottlecaps >= for_trade
  # trade bottlecaps
end

【讨论】：