【Hello Python World】Week 4(1)：用户输入和while循环

第七章主要是继续介绍Python中的输入操作和while，是比较简单的一章

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”。

car = input("What kind of car do you want? ")
print("Let me see if I can find you a " + car)

#输出 What kind of car do you want? 
#输入 "Benz"
#输出 Let me see if I can find you a Benz

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。

client = int(input("How many people of you? "))
if client > 8:
    print("Sorry, there's no table.")
else:
    print("Welcome! Please follow me!")

#输出 How many people of you?
#输入 9
#输出 Sorry, there's no table.

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。

num = int(input("Enter a numbers:"))
if num % 10 == 0:
    print("the nums is times of 10")
else:
    print("the nums is not times of 10")

#输出 Enter a numbers:
#输入 20
#输出 the nums is times 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。

while True:
    thing = input("Please Enter some things you want to add, enter Q to quit:")
    if thing == 'Q':
            break
    print("Ok, we will add " + thing)

#输出 Please Enter some things you want to add, enter Q to quit:
#输入 "apple"
#输出 Ok, we will add apple
#输出 Please Enter some things you want to add, enter Q to quit:
#输入 "milk"
#输出 Ok, we will add milk
#输出 Please Enter some things you want to add, enter Q to quit:
#输入 "Q"

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。

age = int(input("How old are you?"))
if age < 3:
    print("The price is free")
elif age >= 3 and age < 12:
    print("The price is $10")
else:
    print("The price is $15")

#输出 How old are you?
#输入 19
#输出 The price is $15

注意if语句的写法：

• 不能用 &&而用and
• 不能有else if而应该用elif

7-6 三个出口

以另一种方式完成练习7-4或练习7-5，在程序中采取如下所有做法。

• 在while循环中使用条件测试来结束循环。
• 使用变量active来控制循环结束的时机。
• 使用break语句在用户输入'quit'时退出循环。

选择练习7-5:

active = 3
while active > 0:
    active = active - 1
    age = int(input("How old are you? "))
    if age < 3:
        print("The price is free")
    elif age >= 3 and age < 12:
        print("The price is $10")
    else:
        print("The price is $15")

#输出 How old are you?
#输入 19
#输出 The price is $15
#输出 How old are you?
#输入 9
#输出 The price is $10
#输出 How old are you?
#输入 2
#输出 The price is free

while True:
    age = int(input("How old are you? Enter 0 to quit: "))
    if age == 0: 
        break;
    elif age < 3:
        print("The price is free")
    elif age >= 3 and age < 12:
        print("The price is $10")
    else:
        print("The price is $15")

#输出 How old are you? Enter 0 to quit: 
#输入 6
#输出 The price is $10
#输出 How old are you? Enter 0 to quit: 
#输入 2
#输出 The price is free
#输出 How old are you? Enter 0 to quit: 
#输入 15
#输出 The price is $15
#输出 How old are you? Enter 0 to quit: 
#输入 0

7-7 无限循环

编写一个没完没了的循环，并运行它（要结束该循环，可按Ctrl +C，也可关闭显示输出的窗口）。

while True:
    print("in while")

#输出：
#in while
#in while
#in while
#in while
#...

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 = ["A", "B", "C"]
finished_sandwiches = []
while sandwich_orders:
    sandwich = sandwich_orders.pop()
    print("I made " + sandwich + " sandwich")
    finished_sandwiches.insert(0, sandwich)
print("All sandwiches are made")

#输出：
#I made C sandwich
#I made B sandwich
#I made A sandwich
#All sandwiches are made

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 = ["A", 'pastrami', "B", 'pastrami', "C", 'pastrami']
print("The pastrami sandwich has been sold out.")
while 'pastrami' in sandwich_orders:
    sandwich_orders.remove('pastrami')
print(sandwich_orders)

#输出：
#The pastrami sandwich has been sold out.
#['A', 'B', 'C']

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。

surveys = {}
print("Survey begin:")
while True:
    ask = input("If you could visit one place in the world, where would you go? Q to quit\n")
    if ask == 'Q':
        break
    elif ask in surveys.keys():
        surveys[ask] += 1
    else:
        surveys[ask] = 1
for key, value in surveys.items():
    print(str(value) + " people like to go to " + key)

#输出 Survey begin:
#输出 If you could visit one place in the world, where would you go? Q to quit
#输入 "a"
#输出 If you could visit one place in the world, where would you go? Q to quit
#输入 "a"
#输出 If you could visit one place in the world, where would you go? Q to quit
#输入 "b"
#输出 If you could visit one place in the world, where would you go? Q to quit
#输入 "c"
#输出 If you could visit one place in the world, where would you go? Q to quit
#输入 "a"
#输出 If you could visit one place in the world, where would you go? Q to quit
#输入 "Q"
#输出 3 people like to go to a
#输出 1 people like to go to c
#输出 1 people like to go to b