python从入门到实践
"""
chapter7 用户输入和while循环
"""
# 7.1 函数 input()的工作原理:函数input()让程序暂停运行，等待用户输入一些文本
message = input("Tell me something, and I will repeat it back to you: ")
print(message)
# 7.1.1 编写清晰的程序
name = input("Please enter your name: ")
print("Hello, " + name + "!")
prompt = "If you tell us who you are, we can personalize the messages you see."
prompt += "
What is your first name? "
name = input(prompt)
print("
Hello, " + name + "!")
# 7.1.2 使用 int()来获取数值输入
height = input("How tall are you, in inches? ")
height = int(height)
if height >= 36:
print("
You're tall enough to ride!")
else:
print("
You'll be able to ride when you're a little older.")
# 7.1.3 求模运算符
number = input("Enter a number, and I'll tell you if it's even or odd: ")
number = int(number)
if number % 2 == 0:
print("
The number " + str(number) + " is even.")
else:
print("
The number " + str(number) + " is odd.")
# 7.2 while 循环简介
# 7.2.1 使用 while 循环
number = 1
while number <= 5:
print(number)
number += 1
# 7.2.2 让用户选择何时退出
prompt = "
Tell me something, and I will repeat it back to you:"
prompt += "
Enter 'quit' to end the program. "
message = ""
while message != 'quit':
message = input(prompt)
print(message)
# 7.2.3 使用标志 -让while循环更简洁
prompt = "
Tell me something, and I will repeat it back to you:"
prompt += "
Enter 'quit' to end the program. "
flag = True
while flag:
message = input(prompt)
if message == 'quit':
flag = False
else:
print(message)
# 7.2.4 使用 break 退出循环
number = 1
while number < 7:
print(number)
number += 1
if number == 3:
break
print("--------------------")
number = 1
while number < 7:
print(number)
number += 1
if number == 3:
continue
# 7.2.5 在循环中使用 continue
# 打印10以内的所有奇数
print("--------------------")
number = 0
while number < 10:
number += 1
if number % 2 == 0:
continue
print(number)
# 7.2.6 避免无限循环 小心处理while循环，防止无限循环
# 7.3 使用 while 循环来处理列表和字典
# 7.3.1 在列表之间移动元素
# 假设有一个列表，其中包含新注册但还未验证的网站用户；验证这些用户后，如何将他们移到另一个已验证用户列表中呢？
print("--------------------")
unconfirmed_users = ['zhangsan', 'lisi', 'wangwu']
confirmed_users = []
while len(unconfirmed_users) != 0:
user = unconfirmed_users.pop()
confirmed_users.append(user)
print(user + "be confirmed")
# 显示所有已验证的用户
print("
The following users have been confirmed:")
for confirmed_user in confirmed_users:
print(confirmed_user.title())
# 7.3.2 删除包含特定值的所有列表元素
print("7.3.2 --------------------")
users = ['zhangsan', 'lisi', 'wangwu', 'zhangsan2']
print(users)
for user in users:
if user.startswith("zhangsan"):
users.remove(user)
print(users)
print("7.3.2 2--------------------")
users = ['zhangsan', 'lisi', 'wangwu', 'zhangsan2']
print(users)
for user in users:
while user.startswith("zhangsan"):
users.remove(user)
break # 小心while循环带来的问题，少使用while循环
print(users)
# 7.3.3 使用用户输入来填充字典
responses = {}
# 设置一个标志，指出调查是否继续
polling_active = True
while polling_active:
# 提示输入被调查者的名字和回答
name = input("
What is your name? ")
response = input("Which mountain would you like to climb someday? ")
responses[name] = response
# 看看是否还有人要参与调查
repeat = input("Would you like to let another person respond? (yes/ no) ")
if repeat == 'no':
polling_active = False
# 调查结束，显示结果
print("
--- Poll Results ---")
for name, response in responses.items():
print(name + " would like to climb " + response + ".")
练习：
# 7-1 汽车租赁：编写一个程序，询问用户要租赁什么样的汽车，并打印一条消息，如“Let me see if I can find you a Subaru”。
# prompt = "
What kind of car do you want to rent? "
# car = input(prompt)
# print("Let me see if I can find you a " + car + "!")
# 7-2 餐馆订位：编写一个程序，询问用户有多少人用餐。如果超过 8 人，就打印一条消息，指出没有空桌；否则指出有空桌。
# prompt = "
How many people do you have to eat? "
# guest_number = input(prompt)
# if int(guest_number) > 8:
# print("There is no empty table here.")
# else:
# print("Follow me ,pls")
# 7-3 10 的整数倍：让用户输入一个数字，并指出这个数字是否是 10 的整数倍。
# prompt = "
input a number ,I can tell you if it is an integer multiple of 10 "
# number = int(input(prompt))
# if number % 10 == 0:
# print("it is an integer multiple of 10。 ")
# else:
# print("it is not an integer multiple of 10。 ")
#
# 7-4 比萨配料：编写一个循环，提示用户输入一系列的比萨配料，并在用户输入'quit'时结束循环。每当用户输入一种配料后，
# 都打印一条消息，说我们会在比萨中添加这种配料。
# prompt = "
请输入披萨配料： "
# message = ""
# while True:
# message = input(prompt)
# if 'quit' == message:
# break
# else:
# print("我们会在披萨中添加这种配料！")
# 7-5 电影票：有家电影院根据观众的年龄收取不同的票价：不到 3 岁的观众免费；3~12 岁的观众为 10 美元；
# 超过 12 岁的观众为 15 美元。请编写一个循环，在其中询问用户的年龄，并指出其票价。
# prompt = "
请问你今年多大： "
# while True:
# age_str = input(prompt)
# if not str(age_str).isnumeric():
# break
# else:
# age = int(age_str)
# if age < 3:
# print("free!")
# elif age > 3 and age < 12:
# print("10$")
# else:
# print("15$")
# prompt = "
请问你今年多大： "
# flag = True
# while flag:
# age_str = input(prompt)
# if not str(age_str).isnumeric():
# flag = False
# else:
# age = int(age_str)
# if age < 3:
# print("free!")
# # elif age > 3 and age < 12:
# elif 3 < age < 12:
# print("10$")
# else:
# print("15$")
# 7-8 熟食店：创建一个名为 sandwich_orders 的列表，在其中包含各种三明治的名
# 字；再创建一个名为 finished_sandwiches 的空列表。遍历列表 sandwich_orders，对于
# 其中的每种三明治，都打印一条消息，如 I made your tuna sandwich，并将其移到列表
# finished_sandwiches。所有三明治都制作好后，打印一条消息，将这些三明治列出来。
sandwich_orders = ['三明治1', '三明治2', '三明治3']
finished_sandwiches = []
for sandwich in sandwich_orders:
print("I made your tuna sandwich")
finished_sandwiches.append(sandwich)
print(finished_sandwiches)
# 7-9 五香烟熏牛肉（pastrami）卖完了：使用为完成练习 7-8 而创建的列表
# sandwich_orders，并确保'pastrami'在其中至少出现了三次。在程序开头附近添加这样
# 的代码：打印一条消息，指出熟食店的五香烟熏牛肉卖完了；再使用一个 while 循环将
# 列表 sandwich_orders 中的'pastrami'都删除。确认最终的列表 finished_sandwiches 中
# 不包含'pastrami'
sandwich_orders = ['11', 'pastrami', '22', '33', 'pastrami', '44', 'pastrami']
finished_sandwiches = []
print("Pastrami has been sold out")
while 'pastrami' in sandwich_orders:
sandwich_orders.remove('pastrami')
for sandwich in sandwich_orders:
print("I made your " + sandwich + " sandwich.")
finished_sandwiches.append(sandwich)
for sandwich in finished_sandwiches:
print(sandwich)
# 7-10 梦想的度假胜地：编写一个程序，调查用户梦想的度假胜地。使用类似于“If
# you could visit one place in the world, where would you go?”的提示，并编写一个打印调
# 查结果的代码块。
responses = {}
polling_active = True
while polling_active:
name = input("
What's u name?")
place = input("
If you could visit one place in the world, where would you go?")
responses[name] = place
# 看看是否还有人要参与调查
repeat = input("Would you like to let another person respond? (yes/ no) ")
if repeat == 'no':
polling_active = False
# 调查结束，显示结果
print("
--- Poll Results ---")
for name, pl in responses.items():
print(name + " would like to visit " + pl + ".")