Python 中的 while 循环使流程图变得复杂

Question

我将不胜感激：

我试着做一个“那为什么要担心”哲学的形式程序：

我写了这段代码，但我不明白如何让 while 循环在每次用户没有在两个问题中输入“是”或“否”时重复自己。

problem = str(input("Do you have a problem in life? "))
problem = problem.replace(" ", "").lower() #nevermind caps or spaces
while problem:
  if problem not in ("yes","no"):
   print("Please enter YES or NO")
  if problem == "no":
    break
  if problem == "yes": 
   something = str(input("Do you have something to do about it? "))
  something = something.replace(" ","").lower()
  while something:
    if something not in ("yes","no"):
      print("Please enter YES or NO")
    elif: 
     break
print("Then why worry?")

Answer 1

我建议使用 while True 循环，这样你就可以把 input 代码放一次，然后在正确的条件下中断就可以了

while True:
    problem = input("Do you have a problem in life? ").lower().strip()

    if problem not in ("yes", "no"):
        print("Please enter YES or NO")
        continue

    if problem == "no":
        break

    while True:
        something = input("Do you have something to do about it? ").lower().strip()
        if something not in ("yes", "no"):
            print("Please enter YES or NO")
            continue
        break
    break

print("Then why worry?")

使用海象运算符 (py>=3.8) 可以更轻松地完成

while (problem := input("Do you have a problem in life? ").lower().strip()) not in ("yes", "no"):
    pass
if problem == "yes":
    while (something := input("Do you have something to do about it? ").lower().strip()) not in ("yes", "no"):
        pass

print("Then why worry?")

Answer 2

你的算法是线性的，没有循环。因此，唯一需要循环的地方是当您尝试从用户那里获得正确的响应时。所以，我建议你把它移到一个函数中，然后你的例子变成这样：

def get_user_input(prompt):
    while True:
        reply = input(prompt).replace(" ", "").lower()
        if reply in ['yes', 'no']:
            return reply
        print("Please enter YES or NO")

problem_exists = get_user_input("Do you have a problem in life? ")
if problem_exists == 'yes':
    action_possible = get_user_input("Do you have something to do about it? ")
print("Then why worry?")

Python 中的 while 循环使流程图变得复杂

Flowchart getting complicated with while loops in Python

python

loops

while-loop