# _*_ coding:utf-8 _*_##########if语句############，今天小编就来聊一聊关于python 怎么用if语句?接下来我们就一起去研究一下吧!
python 怎么用if语句
# _*_ coding:utf-8 _*_
##########if语句############
#一个简单的例子
cars = ['audi', 'BMW', 'Subaru', 'toyota']
for car in cars:
if car == 'bmw'：
print(car.upper())
else:
print(car.title())
-------------------------------------------
Audi
BMW
Subaru
Toyota
-------------------------------------------
#条件测试
answer = 17
if answer!= 42:
print("That is not the correct answer.please try again!")
-------------------------------------------
That is not the correct answer.please try again!
-------------------------------------------
#检查多个条件
#使用and检查多个条件
age_0 = 22
age_1 = 18
print(age_0 >= 21 and age_1>=21)
age_1 = 21
print(age_0 >= 21 and age_1>=21)
-------------------------------------------
False
True
-------------------------------------------
#使用or检查多个条件
age_0 =22
age_1 = 18
print(age_0 >=21 or age_1 >= 21)
age_0 = 18
print(age_0 >= 21 or age_1 >= 21)
-------------------------------------------
True
False
-------------------------------------------
#使用in检查特定值是否包含在列表中
requested_toppings = ['mushrooms', 'onions', 'pineapple']
print('mushrooms' in requested_toppings)
print('pepperoni' in requested_toppings)
-------------------------------------------
True
False
-------------------------------------------
#使用not in检查特定值是否不包含在列表中
banned_users = ['andrew', 'carolina', 'david']
user = 'marie'
if user not in banned_users:
print(user.title() ",you can post a response if you wish.")
-------------------------------------------
Marie,you can post a response if you wish.
-------------------------------------------
#布尔表达式(布尔表达式的结果要么为True，要么为False)
game_active = True
can_edit = False
#if 语句
#简单的if语句
age = 19
if age >=18:
print("You are old enough to votel.")
print("Have you registered to vote yet?")
-------------------------------------------
You are old enough to votel.
Have you registered to vote yet?
-------------------------------------------
#if-else 语句
age = 17
if age>= 18:
print("You are old enough to votel.")
print("Have you registered to vote yet?")
else:
print("Sorry, you are too young to vote.")
print("Please register to vote as soon as you turn 18!")
-------------------------------------------
Sorry, you are too young to vote.
Please register to vote as soon as you turn 18!
-------------------------------------------
#if-elif-else语句
age = 12
if age < 4:
print("Your admission cost is $0.")
elif age < 18:
print("Your admission cost is $5.")
else:
print("Your admission cost is $10.")
-------------------------------------------
Your admission cost is $5.
-------------------------------------------
if age < 4:
price = 0
elif age < 18:
price = 5
else:
price = 10
print("Your admission cost is $" str(price) ".")
-------------------------------------------
Your admission cost is $5.
-------------------------------------------
#使用多个elif代码块
if age < 4:
price = 0
elif age < 18:
price = 5
elif age < 65:
price = 10
else:
price = 5
print("Your admission cost is $" str(price) ".")
-------------------------------------------
Your admission cost is $5.
-------------------------------------------
#省略else代码块
if age < 4:
price = 0
elif age < 18:
price = 5
elif age < 65:
price = 10
elif age >= 65:
price = 5
print("Your admission cost is $" str(price) ".")
-------------------------------------------
Your admission cost is $5.
-------------------------------------------
#测试多个条件
requested_toppings = ['mushrooms', 'extra cheese']
if 'mushrooms' in requested_toppings:
print("Adding mushrooms.")
if 'extra cheese' in requested_toppings:
print("Adding extra cheese.")
if 'pepperoni' in requested_toppings:
print("Adding pepperoni.")
print("\nFinished making your pizza!")
-------------------------------------------
Adding mushrooms.
Adding extra cheese.
Finished making your pizza!
-------------------------------------------
#使用if语句处理列表
requested_toppings = ['mushrooms', 'green peppers', 'extra cheese']
for requested_topping in requested_toppings:
if requested_topping == 'green peppers':
print("Sorry,we are out of green peppers right now.")
else:
print("Adding " requested_topping ".")
print("\nFinished making your pizza!")
-------------------------------------------
Adding mushrooms.
Sorry,we are out of green peppers right now.
Adding extra cheese.
Finished making your pizza!
-------------------------------------------
#确定列表不是空的
requested_toppings = []
if requested_toppings:
for requested_topping in requested_toppings:
print("Adding " requested_topping ".")
print("\nFinished making your pizza!")
else:
print("Are you sure you want a plain pizza?")
-------------------------------------------
Are you sure you want a plain pizza?
-------------------------------------------
#使用多个列表
available_toppings = ['mushrooms', 'olives', 'green peppers', 'pepperoni', 'pineapple', 'extra cheese']
requested_toppings = ['mushrooms', 'french fries', 'extra cheese']
for requested_topping in requested_toppings:
if requested_topping in available_toppings:
print("Adding " requested_topping ".")
else:
print("Sorry, we don't have " requested_topping ".")
print("\nFinished making your pizza.")
-------------------------------------------
Adding mushrooms.
Sorry, we don't have french fries.
Adding extra cheese.
Finished making your pizza.
-------------------------------------------
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