Collat z序列 - 最后得到无[重复]

Question

这个问题在这里已有答案：

• What is the formal difference between “print” and “return”? [duplicate] 6个答案

学习Al Sweigart的“自动无聊的东西”。在第3章的最后，Collat​​z序列作为实践给出。输出似乎正确，但最后一行中有“无”。在下面的代码中，我猜测当p = 1时，它会退出while循环，然后没有任何内容可以打印，所以它给出了None（？）。有人可以指出我为什么添加None的正确方向，以及如何解决它？

请参阅下面的代码并进一步了解示例结果：

def collatz (p):
    while p != 1:
        if p % 2 ==0:
           p = (p//2)
           print(p)
        else:
           p = ((3*p) + 1)
           print(p) 

print ('Select a number between 1 and 10')
entry = float(input())
number = round(entry)
if number >10 or number <1:
   print('Your selection must between 1 and 10. Please try again')
else:       
   Program = collatz(number)
   print (Program)

**示例结果：如果我输入数字为3，我得到：

3
10
5
16
8
4
2
1
None

Answer 1

正如评论中已经指出的那样，你的函数返回None。我以为我会把你的功能变成一个生成器，你可以迭代并以这种方式打印值。这有几个优点，例如使代码更灵活和可重用：

def collatz (p):
    while p != 1:
        if p % 2 == 0:
           p = p / 2 # You don't need the double slash here because of the if before it
        else:
           p = (3*p) + 1

        yield p 

print('Select a number between 1 and 10')
number = int(input()) # You really want int here I think and leave out the rounding

if 1 <= number <= 10: # Slightly more pythonic
   for sequence_item in collatz(number):
       print(sequence_item)
else:
   print('Your selection must between 1 and 10. Please try again')

随意提出任何问题或在可能错误的假设下纠正我！ :)