Question

我是红宝石的新手，我很难弄清楚如何计算随机旅行时间，直到它超过1000英里。到目前为止，我无法弄清楚它为什么不输出结果，它只是留在用户输入。请帮忙

def travel_time()
    printf "Pick a vehicle: \n"
    printf "1.  Bicycle \n"
    printf "2.  Car \n"
    printf "3.  Jet Plane \n"
    puts "Choose 1-3: \n"
    vehicle = gets.chomp

  case vehicle
    when "1"
        #Bicycle: 5-15 miles per hour
        time = 0
        distance = 0
        until distance > 1000 do
         speed = Random.rand(5...15)
         distance = speed * 1
         time = time + 1
        end
        puts "The number of hours it took to travel 1000 miles was #{time} hours"
    when "2"
        #Car: 20-70 miles per hour
        time = 0
        distance = 0
        until distance > 1000 do
        speed = Random.rand(20...70)
        distance = speed * 1
        time = time + 1
        end
        puts "The number of hours it took to travel 1000 miles was #{time} hours"

    when "3"
        #Jet Plane: 400-600 miles per hour
        time = 0
        distance = 0
        until distance > 1000 do
        speed = Random.rand(400...600)
        distance = speed * 1
        time = time + 1
        end
        puts "The number of hours it took to travel 1000 miles was #{time} hours"
    end
end
travel_time

Answer 1

这里有一个无限循环：

until distance > 1000 do
  speed = Random.rand(5...15)
  distance = speed * 1
  time = time + 1
end

这个循环永远不会起作用，因为最大值distance可以得到15，所以我想你想要添加到distance，而不是替换它;儿子尝试使用+=代替=：

until distance > 1000 do
  speed = Random.rand(5...15)
  distance += speed * 1
  time = time + 1
end

每种情况下的所有循环都是一样的。

如何保存最高速度并将其返回到像我这样的语句中做过吗？

一种方法是在max_speed大于speed时添加另一个变量（即speed）并为其指定max_speed值：

time = 0
distance = 0
max_speed = 0

until distance > 1000 do
  speed = Random.rand(5...15)
  max_speed = speed if speed > max_speed
  distance += speed * 1
  time = time + 1
end

puts "The maximum speed was #{max_speed} miles per hour"

另一种方法是使用数组（虽然我更喜欢第一种选择）：

speed = []

until distance > 1000 do
  speed << Random.rand(5...15)
  distance += speed.last * 1
  time = time + 1
end

puts "The maximum speed was #{speed.max} miles per hour"

Answer 2

你实际上并没有总结距离 - 距离永远不会超过1000

until distance > 1000 do
  speed = Random.rand(5...15)
  distance = speed * 1 # will never equal more than 15
  time = time + 1
end

你可能想要

distance += speed * 1 # not sure why you're multiplying by 1 though

Answer 3

作为样式注释：不要使用case语句作为控制流，如if / then语句。只需使用它们来设置值，并将其他所有内容移出。这可以消除大量冗余代码。例如：

time = 0
distance = 0
until distance > 1000 do   
  speed = case vehicle
    when "1" then Random.rand(5...15)    #Bicycle
    when "2" then Random.rand(20...70)   #Car
    when "3" then Random.rand(400...600) #Plane
    end
  distance += speed * 1
  time = time + 1
end
puts "The number of hours it took to travel 1000 miles was #{time} hours"

红宝石旅行时间

3 个答案: