# 布尔表达式
isOpen = True
isClose = False

# if 语句
a = 3
if a == 0:
 pass
elif a == 1:
 pass
elif a == 2:
 pass
else:
 pass

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

for car in cars:
 if car == "bmw" or car == "audi":
 print(car.upper())
 else:
 print(car.title())

age = 12
price = 0

if age < 4:
 price = 0
elif age < 18:
 price = 25
elif age < 65:
 price = 40
elif age >= 65:
 price = 20

print(f"Your admission cost is ${price}.")

requested_toppings = []

# 在 if 语句中将列表名用作条件表达式时,Python 将在列表至少包含一个元素时返回 True,在列表为空时返回 False。
# 对于数值 0、空值 None、单引号空字符串 ''、双引号空字符串 ""、空列表 []、空元组 ()、空字典 {},都会返回 False。
if requested_toppings:
 for requested_topping in requested_toppings:
 print(f"Adding {requested_topping}.")
 print("\nFinished making your pizza!")
else:
 print("Are you sure you want a plain pizza?")

available_toppings = [
 "mushrooms",
 "olives",
 "green peppers",
 "pepperoni",
 "pineapple",
 "extra cheese",
]
requested_toppings = ["mushrooms", "french fries", "extra cheese"]

for requested_topping in requested_toppings:
 # 判断特定的值是否在列表中
 if requested_topping in available_toppings:
 print(f"Adding {requested_topping}.")
 else:
 print(f"Sorry, we don't have {requested_topping}.")


banned_users = ["andrew", "carolina", "david"]
user = "marie"

# 判断特定的值是否不在列表中
if user not in banned_users:
 print(f"{user.title()}, you can post a response if you wish.")

if (eggs := 7 + 5) == 12:
 print(f"eggs: {eggs}")

# 赋值表达式使 eggs 成为外部作用域中的一个有效变量,因而可以在条件之外输出其值。
print(f"eggs: {eggs}")