Python-IF语句

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''' Char 5 IF '''

cars=['audi','bmw','subaru','toyota']

for car in cars:

if car=='bmw':

print(car.upper())

else:

print(car.title())

# ~ 相等运算符== 在它两边的值相等时返回True ，否则返回False

car='audi' # ❶

car=='bmw' # ❷

# ~ 一个等号是陈述；对于❶处的代码，可解读为“将变量car 的值设置为'audi' ”。

# ~ 两个等号是发问；对于❷处的代码，可解读为“变量car 的值是'bmw' 吗？”。大多数编程语言

# ~ 使用等号的方式都与这里演示的相同。

car='Audi'

if car.lower()=='audi':

print("\n this car is audi, it is true\n")

# ~ 检查是否不相等 !=

re='mushrooms'

if re != 'annnnn':

print("hold the list\n")

# ~ 比较数字

age=20

if age==18:

print("this guy is pretty young.\n")

else:

print("er.....not 18 yet\n")

if age != 50:

print("this is not the correct answer. please try again!\n")

if age > 10:

print("age is over 10.\n")

# ~ 检查多个条件 and or

location='toronto'

age=22

if location=='toronto' and age >= 20:

print("this guy comes from toronto and he is allowed to drink beer.\n")

if location!="london" and age >= 20:

print("this guy is not coming from toronto but he is allowed to drink here\n")

if age

print("sorry, you can't order any drink.\n")

if location=="toronto" or age

print("toronto's student?? needs his/her ID to verify\n")

# ~ 检查特定值是否包含在列表中

stu_list=['d','e','t','a']

if 'd' in stu_list:

print("d in the list!\n")

# ~ 检查特定值是否不包含在列表中

banned_users=['chang','gao','zhou','wang']

user='hao'

if user not in banned_users:

print("Hi " + user.title() + ", we'll grant you normal access.\n")

else:

print("sorry, we can't grant you access. pls contact local admin\n")

# ~ 布尔表达式

# ~ 随着你对编程的了解越来越深入，将遇到术语布尔表达式 ，它不过是条件测试的别名。与条件表达式一样，

# ~ 布尔表达式的结果要么为True ，要么为False 。

# ~ 布尔值通常用于记录条件，如游戏是否正在运行，或用户是否可以编辑网站的特定内容：

car = 'subaru'

print("\nIs car == 'subaru'? I predict True.")

print(car == 'subaru')

print("\nIs car == 'audi'? I predict False.")

print(car == 'audi')

#try;

#5-2

loca1='toronto'

loca2='london'

localist=['freiBUrg','Beijing','LONDON','shanghai','TORONTO']

ageone=22

agetwo=60

if loca1=='toronto':

print("location is toronto, this is ")

print(loca1=="toronto")

if ageone >= 20 and agetwo

print("this guy could drink maximum 500ml beer per day.\n")

if ageone = 60:

print("- you can't drink according to your age")

trip="shanghai"

if trip not in localist:

print("\nsorry, pls try another location, we can't find it in our list\n")

else:

print("\nok plesse check in here\n")

tt="kk"

if tt != "kkk":

print("error\n")

# if 语句; P46

yard=1900

if yard >=2000:

print("\nyou are our VIP")

print('are you registed to this meeting?\n')

else:

print("sorry, you are currently on our waiting list.\n")

'''经常需要检查超过两个的情形，为此可使用Python提供的if-elif-else 结构'''

'''Python并不要求if-elif 结构后面必须有else 代码块'''

''' 0-18 19-59 others;'''

ticket=16

if 0

print("this ticket is free for you.\n")

elif ticket

print("this ticket is $10.\n")

else:

print("this ticket is $5.\n")

# ~ or

if ticket

print("this ticket is free for you.\n")

elif ticket

print("this ticket is $10.\n")

else:

print("this ticket is $5.\n")

# ~ or

if ticket

price="free"

elif ticket

price="$10"

else:

price="$5"

print("your ticket cost is " + price + ".")

'''测试多个条件 if '''

requested_toppings = ['mushrooms', 'extra cheese']

if 'mushrooms' in requested_toppings:

print("\nadding mushrooms.\n")

if 'pepperoni' in requested_toppings:

print('\nadding pepperoni.\n')

if 'extra cheese' in requested_toppings:

print('\nadding extra cheese.\n')

#try:

#5-3:

alien_color='red'

if 'green' in alien_color:

gains=5

print("congras, your just got " + str(gains) + " points.")

if 'red' in alien_color:

gains=5

print("congras, your just got " + str(gains) + " points.")

# 5-4

if 'green' in alien_color:

gains=5

print("congras, your just got " + str(gains) + " points.")

else:

gains=10

print("congras, your just got " + str(gains) + " points.")

# 5-5;

if 'green' in alien_color:

gains=5

elif 'yellow' in alien_color:

gains=10

elif 'red' in alien_color:

gains=15

print("congras, your just got " + str(gains) + " points.")

#5-6

age=65

if age

print("\nthis is a baby.\n")

elif age

print("this is a toddler.\n")

elif age

print("this is a kid.\n")

elif age

print("this is a young.\n")

elif age

print("this is an adult.\n")

else:

print("this is a senior citizen.\n")

'''　使用if 语句处理列表'''

#通过创建一个列表，在其中包含顾客点的配料

requested_toppings = ['mushrooms', 'green peppers', 'extra cheese']

for toppings in requested_toppings:

print("adding " + toppings + ".")

print('\nfinished making your pizza!\n')

#然而，如果比萨店的青椒用完了，该如何处理呢？为妥善地处理这种情况，可在for 循环中包含一条if 语句：

requested_toppings = ['mushrooms', 'green peppers', 'extra cheese']

for toppings in requested_toppings:

if toppings=='green peppers':

print('sorry, we are out of green peppers')

else:

print("adding " + toppings + ".")

print('\nfinished making your pizza!\n')

#确定列表不是空的

requested_toppings=[]

if requested_toppings:

for toppings in requested_toppings:

print("adding " + toppings + ".")

else:

print("\nare you sure you want a plain pizza?\n")

# 使用多个列表

'''下面的示例定义了两个列表，其中第一个列表包含比萨店供应的配料，而第二个列表包含顾客点的配料。这次对

于requested_toppings 中的每个元素，都检查它是否是比萨店供应的配料，再决定是否在比萨中添加它：'''

available_toppings = ['mushrooms', 'olives', 'green peppers',

'pepperoni', 'pineapple', 'extra cheese']

requested_toppings = ['mushrooms', 'french fries', 'extra cheese']

for order in requested_toppings:

if order in available_toppings:

print('adding ' + order + '.')

else:

print('\nsorry, we dont have ' + order + '.')

print("\nFinished making your pizza!")

#try:

#5-8 5-9

name=['zhang','wang','li','zhao','hou']

check=[]

if name:

for check in name:

if 'zhang' in check:

print('Hello Zhang, would you like to see a staus report?\n')

else:

print('Hello ' + check.title() + ', thank you for looging in again.')

else:

print('\nWe need to find some users!\n')

#5-10

current_users=['zhang','wang','li','zhao','hou']

new_users=['hang','ZHOU','LI','wang','gao']

if new_users:

for check in new_users:

if check.lower() in current_users:

print('it is our existed user.\n')

else:

print('sorry, we can not find this user\n')

else:

print('\nSorry, please list the new user.\n')

#5-11

numlist=list(range(1,11))

for check in numlist:

if check==1: print('1st')

elif check==2: print('2nd')

elif check==3: print('3rd')

else: print(str(check) + 'th')

'''在本章中，你学习了如何编写结果要么为Ture 要么为False 的条件测试。你学习了如何编写简单的if

语句、if-else 语句和if-elif-else 结构。在程序中，你使用了这些结构来测试特定的条件，以确定这些

条件是否满足。你学习了如何在利用高效的for 循环的同时，以不同于其他元素的方式对特定的列表元素进行处理。你还再次学习了Python就代码格式方面提出的建议，这可确保即便你编写的程序越来越复杂，其代码依然易于阅读和理解。'''