python入门-WHILE循环

1 使用while循环

current_number= 1
while current_number <= 5:
    print(current_number)
    current_number += 1

2 让用户选择退出

prompt = "tell me somthing, and i will repeat it back to you"
prompt = "\nEnter 'quit' to end the program"

message = ""
while message != 'quit':
    message=input(prompt)

    if message!='quit':
        print(message)

3 使用标志

prompt = "tell me somthing, and i will repeat it back to you"
prompt = "\nEnter 'quit' to end the program"

active = True
while active:
    message = input(prompt)

    if message == 'quit':
        active = False
    else:
        print(message)

4 使用break退出循环

prompt = "\nPlease enter the name of a city you have visited:"
prompt += "\n(enter 'quit' when you are finished.)"

while True:
    city = input(prompt)

    if city == 'quit':
        break
    else:
        print("I'd love to go to" + city.title() + "!")

5 在循环中使用continue

current_number = 0
while current_number < 10:
    current_number += 1
    if current_number % 2 ==0:
        continue

    print(current_number)

6 使用while循环来处理列表和字典

unconfirmed_users = ['alice','brian','candace']
confirmed_users = []

while unconfirmed_users:
    current_user = unconfirmed_users.pop()

    print("verifying user:" + current_user.title())
    confirmed_users.append(current_user)

print("\n the following users have been confirmed:")
for confirmed_user in confirmed_users:
    print(confirmed_user.title())

7 删除特定的列表元素

pets = ['dog','cat','dog','goldfish','cat','rabbit','cat']
print(pets)

while 'cat' in pets:
    pets.remove('cat')

print(pets)

8使用用户输入来填充字典

responses = {}
polling_active = True

while polling_active:
    name = input("\n what is your name?")
    response = input("which mountain would you like to climb someday")

    responses[name] = response

    repeat = input("would you like to let another person respond?(yes or no")
    if repeat == 'no':
        polling_active = False

print("\n --poll results--")
for name,response in responses.items():
    print(name + "would like to climb" + response + ".")