#char 5 if语句
#5.1 结构:if:
# sth to do
#else:
#sth to do
cars=["audi","bmw","subaru","toyota"]
for car in cars:
if car=="bmw":
print(car.upper())
else:
print(car.title())
#5.2条件测试
#5.2.1 检查是否相等
car="bmw"
print(car=="bmw")
print(car=="audi")
#5.2.2 区分大小写
car="BMW"
print(car=="bmw")
print(car.lower()=="bmw")
#5.2.3检查是否相等
requested_topping="mushroom"
if requested_topping != "anchovies":
print("hold the anchovies")
#5.2.4 比较数字:
age=19
print(age==19)
#5.2.5检查多个条件:
#采用and检查多个条件
age_0=22
age_1=19
print(age_0>15 and age_1>15)
#采用or
print(age_0 >20 or age_1 >20)
#5.2.6 检查特定值是否在列表中
requested_topping=["mushroom","onions","pineapple"]
print("mushroom"in requested_topping)
banned_users=["andrew","carolina","david"]
user="marie"
if user not in banned_users:
print(user.title()+" you can post a respon if you wish")
#5.3 if和 if_else语句
age=19
if age >=18:
print("you are old enough to vote")
age_0=15
if age_0 >= 18:
print("you are old enough to vote")
else:
print("sorry,you are too young to vote")
#5.3.3 is-elif-else结构:
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")
#另一结构:
age=12
if age <4:
price=0
elif age <18:
price=5
else:
price=10
print("you admission cost is "+str(price))
#使用多个elif模块
age=79
if age <4:
price=0
elif age <18:
price=5
elif age<65:
price=10
else:
price=5
print("you admission cost is "+str(price))
#省略else模块,即可以通过所有的elif囊括所有的范围值:
if age <4:
price=0
elif age <18:
price=5
elif age<65:
price=10
elif age>-65:
prince=5
print("you admission cost is "+str(price))
#测试多个条件:
requested_topping=["mushroom","extra cheese"]
if "mushroom" in requested_topping:
print("adding mushroom")
elif "pepperoni" in requested_topping:
print("adding pepperoni")
elif "extra cheese" in requested_topping:
print("adding extra")
print("\nfinish your ording")
requested_topping=["mushroom","extra cheese"]
if "mushroom" in requested_topping:
print("adding mushroom")
if "pepperoni" in requested_topping:
print("adding pepperoni")
if "extra cheese" in requested_topping:
print("adding extra")
print("\nfinish your ording")
#如果使用if-elif结果,当程序走到判定正确的位置,会跳出直接输出结果,所以如果有多个判定条件,需要使用多个if语句
#5.4
requested_toppings=["mushroom","green peppers","extra cheese"]
for requested_topping in requested_toppings:
print("adding"+requested_topping+".")
print("\nfinish making the pizza")
requested_toppings=["mushroom","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")
print("adding"+requested_topping+".")
print("\nfinish making the pizza")
#5.4.2确定列表是否为空
requested_toppings=[]
if requested_toppings:
for requested_topping in requested_toppings:
if requested_topping=="green peppers":
print("sorry,we are out of green peppers right now")
print("adding"+requested_topping+".")
print("\nfinish making the pizza")
else:
print("you are sure you want a pizza?")
#5.4.3 使用多个列表
avaliable_toppings=["mushroom","olives","green peppers",
"pepperoni","pineapple","extra cheese"]
requested_toppings=["mushroom","frensh fries","extra cheese"]
for requested_topping in requested_toppings:
if requested_topping in avaliable_toppings:
print("add "+requested_topping)
else:
print("sorry, wo do not have"+requested_topping)
print("\nfinish making pizza")
课后题
#5-1
#5-2
str_1="abc"
str_2="hijk"
str_3="efg"
print(len(str_1)==len(str_2))
print(len(str_1)==len(str_3))
str_4="ABC"
print(str_4.lower()==str_1)
a=24
b=13
c=46
print(a==b)
print(a>b)
print(a
print(a>=b)
print(a<=b)
print(len(str_1)==len(str_4) and len(str_1)==len(str_3))
print(len(str_1)==len(str_4) or len(str_1)==len(str_3))
numbers=[a,b,c]
print(numbers)
d=24
e=25
if d in numbers:
print("d is in the numbers")
if e not in numbers:
print("e is not in the numbers")
#5-3:
alien_color="green"
if alien_color == "green":
print(" you got 5 points")
if alien_color=="red":
print("you got 10 points")
#5-4
if alien_color=="green":
print("you got 5 points")
else:
print("you got 10 points")
if alien_color == "green":
print("you got 5 points")
if alien_color != "green":
print(" you got 10 points")
#5-5
if alien_color == "green":
print("you got 5 points")
elif alien_color ==" yellow":
print("you got 10 points")
elif alien_color=="red":
print("you got 15 points")
#5-6
age=22
if age<2:
stage="baby"
elif age<4:
stage="children"
elif age <13:
stage="teenager"
elif age<20:
stage="youth"
elif age <65:
stage="adul"
else:
stage="elder"
#5-7
favourite_fruit=["apple","orange","banana"]
if "orange" in favourite_fruit:
print("you really like banana")
if "apple" in favourite_fruit:
print("you really like banana")
if "banana" in favourite_fruit:
print("you really like banana")
if "pear" in favourite_fruit:
print("you really like banana")
if "peach" in favourite_fruit:
print("you really like banana")
#5-8
admin_list=["Mike","Sarah","Jack","Rose","Tom","admin"]
for name in admin_list:
if name == "admin":
print(name + " would you like to see some status report")
else:
print("Hello"+name+" , thanks for logging")
#5-9
del admin_list[0:6]
print(admin_list)
if admin_list:
for name in admin_list:
# if name == "admin":
# print(name + " would you like to see some status report")
print("Hello"+name+" , thanks for logging")
else:
print("we need to find some users")
#5-10:
current_user=["Mike","Sarah","Jack","Rose","Tom"]
new_users=["Mike","Sarah","Johnson","John","Kimi"]
for name in new_users:
for i in range(len(current_user)):
current_user[i]=current_user[i].lower()
if name.lower() in current_user:
print("you should set another name")
else:
print("Your account"s name is avaliable")
#5-11:
numbers=list(range(1,11))
for number in numbers:
if number==1:
print(str(number)+"st")
if number==2:
print(str(number)+"nd")
if number ==3:
print(str(number)+"rd")
else:
print(str(number)+"th")