python中的While循环和范围数

正在为学校编写一个代码，我需要对其进行修改，以便只允许用户输入0到20o的范围。这是到目前为止的代码。每次我尝试放置一个while循环时，它都不起作用，我仍然可以输入任何高于200的值。任何帮助都将不胜感激

import turtle  #allows access to a collection of Python functions that make it possible to draw

Jane = turtle.Turtle()  #creates a "turtle" to do our drawing for us; we will call the turtle Jane

# the next four lines get input from the user so we know how tall to make the bars in the graph

bar1 = int(input("What is the height of the first bar?" ))

bar2 = int(input("What is the height of the second bar?" ))

bar3 = int(input("What is the height of the third bar?" ))
  
bar4 = int(input("What is the height of the fourth bar? "))
 
#the turtle always starts out facing left; the next line rotates it so it faces up

Jane.left(90)

#next we will create a function that will draw one bar of the bar graph

#the function requires us to pass the height of the bar into it

def bar(height):
    
    #Jane will make a line that is as long as the height that the user inputted
    
    Jane.forward(height)
    
    #now we will turn Jane to the left to make the top of the bar
    
    Jane.left(90)
    
    #now Jane needs to more forward to draw the top of the bar
    
    Jane.forward(20)
    
    #now Jane needs to turn left 
     
    Jane.left(90)
    
    #now Jane needs to draw a line that is as long as the height
    
    Jane.forward(height)
    
    #now Jane needs to rotate 180 degrees to be ready for the next bar
    
    Jane.right(180)

#now we will call the function four times--one for each bar. Notice that

#we will go in the order 4-3-2-1, since the bars will be drawn from right to left

bar(bar4)

bar(bar3)

bar(bar2)

bar(bar1)

像这样

def limit_input(prompt):
    while True:
        value = int(input(prompt))
        if value < 200:
            return value
        print( "Please keep your value below 200.")

bar1 = limit_input("What is the height of the first bar?")
bar2 = limit_input("What is the height of the second bar?")
bar3 = limit_input("What is the height of the third bar?")
bar4 = limit_input("What is the height of the fourth bar?")

def limit_输入（提示）：
尽管如此：
值=int（输入（提示））
如果值<200：
返回值
打印（“请将您的值保持在200以下。”）
bar1=限制\输入（“第一个条的高度是多少？”）
bar2=限制输入（“第二个条的高度是多少？”）
bar3=限制输入（“第三个条的高度是多少？”）
bar4=限制输入（“第四个条的高度是多少？”）

---

留给读者的一个练习是添加一个

try

/

除了ValueError

子句，以便在用户键入数字以外的其他内容时捕获。

请查看此代码。我想你正在寻找这样的代码

import turtle

Jane = turtle.Turtle()

bars = []
for i in range(4):
    height = 201
    while height > 200:
        height = int(input(f'What is the height of the {i + 1}. bar? (from 1 to 200))'))
    bars.append(height)

Jane.left(90)


def bar(height):
    Jane.forward(height)
    Jane.left(90)
    Jane.forward(20)
    Jane.left(90)
    Jane.forward(height)
    Jane.right(180)


for b in bars:
    bar(b)

---

这里没有试图限制范围的东西。是否需要限制所有输入？如果是这样，那么显而易见的答案是创建一个函数，可能称为

limited\u input

，它接受提示字符串作为参数。它可以执行while循环并一直执行提示，直到值在范围内。您不能在哪里放置while循环，您想在哪里放置while循环？您不需要

返回值

而不仅仅是

返回

？Duh。我将修复这个愚蠢的错误。对于条形图中的b，索引或

会更清晰：

/

条形图（b）

。实际上，每次您为范围内的x（len（y））编写

：

（基本上就是您编写的），都有更好的方法。您是对的。我正在编辑代码。非常感谢。