####if語(yǔ)句###
cars=['audi','bmw','subaru','toyota']
for car in cars:
if car=='bmw':?? #==檢查是否相等? 即相等時(shí)返回Ture，不相等時(shí)返回Flase
print(car.upper())
else:
print(car.title())

cars=['audi','bmw','subaru','toyota']
for car in cars:
if car !="bmw":?? #!=檢查是否不相等? 即不相等時(shí)返回Ture，相等時(shí)返回Flase
print(car.upper())
else:
print(car.lower())

#補(bǔ)python終端檢查是否相等
#>>>car='bmw'
#>>>car=='bmw'則輸出Ture 否則返回Flase, !=同理

#if例子
#檢查一個(gè)人是否是20歲(單個(gè)條件)
answer=18??
if answer!=20:? #當(dāng)然條件可以是大于小于等等 <,>,<=,>=,等等
print('That id not the correct answer,Please try again!')

#檢查多個(gè)條件 and ###關(guān)鍵字or與and類似 不予列舉
answer=18??
if answer>=17 and answer<=20:
print('That id not the correct answer,Please try again!')
#靈活運(yùn)用 可對(duì)多個(gè)人進(jìn)行檢查
answer_1=18
answer_2=20?
if answer_1>=16 and answer_1<=20 and answer_2<30:
print('That id not the correct answer,Please try again!')

##檢查特定值是否在列表中:可利用python終端來(lái)執(zhí)行##
#1.>>>cars=['audi','bmw','subaru','toyota']
#>>>"bmw" in cars
#2.
cars=['audi','bmw','subaru','toyota']
car='bmw'
if car in cars:? #in前加not即沒有在列表內(nèi)
print(car.title()+' '+"in the list")
######
#if-elif-else結(jié)構(gòu) ##只能測(cè)試指定一個(gè)條件(通過(guò)一個(gè)測(cè)試條件將跳過(guò)余下的測(cè)試)#
#可根據(jù)需要使用任意數(shù)量的elif代碼塊
age=15
if age<4:
price=0 #print("Your admission cost is $0")
elif age<18:
price=5? #print("Your admission cost is $5")
else:
price=10? #print("Your admission cost is $10")
print("Your admission cost is $"+str(price)+".")#str()函數(shù)：將某一個(gè)類型強(qiáng)制轉(zhuǎn)換為字符串型。如，a = 1，a的類型就是數(shù)值型，a = str(a)，a就是字符串型了
##測(cè)試多個(gè)條件
print('\n')
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("Finished making your pizza!")
#與for循環(huán)連用 （檢查列表元素中有無(wú)特殊元素）
#披薩店滿足顧客的單個(gè)條件
print('\n')
requested_toppings=['mushrooms','extra cheese','pepperoni','green pappers']
for requested_topping in requested_toppings:
if requested_topping=='pepperoni':
print("Sorry,we are out of pepperoni right now.")
else:
print('Adding '+requested_topping+'.')
print('Finished making your pizza!')
#披薩店滿足顧客的多個(gè)條件
print('\n')
available_toppings=['mushrooms','extra cheese','pepperoni','green pappers','olives']
requested_toppings=['mushrooms','extra cheese','pineapple']
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+'.')
#判斷列表是否為空
print('\n')
requested_toppings=[]
if requested_toppings:? #如果該列表為空時(shí)返回False；至少有一個(gè)元素時(shí)返回True，進(jìn)行下面的for循環(huán)
? for requested_topping in requested_toppings:
? print('Adding '+requested_topping+'.')
else:
print("Are you sure you want a plain pizza?")