#一个简单的示例
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
#检查是否相等
car='bmw'
car=='bmw'
True
car='audi'
car=='bmw'
False
#检查是否相等时忽略大小写
car='Audi'
car=='audi'
False
car='Audi'
car.lower()=='audi'
True
car
‘Audi’
#检查是否不相等
requested_topping='mushrooms'
if requested_topping!='anchovices':
print('Hold the anchovices!')
Hold the anchovices!
#数值比较
age=18
age==18
True
answer=17
if answer!=42:
print('This is not the correct answer.')
This is not the correct answer.
age=18
age<21
True
age=18
age>=21
False
#检查多个条件
age_0=22
age_1=18
age_0>=21 and age_1>=21
False
age_0=22
age_1=18
age_1=22
age_0>=21 and age_1>=21
True
age_0=22
age_1=18
age_0>=21 or age_1>=21
True
age_0=22
age_1=18
age_0=18
age_0>=21 or age_1>=21
False
#检查特点值是否包含在列表中
requested_troppings=['mushrooms','obinions','pineapple']
'mushrooms' in requested_troppings
True
requested_troppings=['mushrooms','obinions','pineapple']
'pepperoni' in requested_troppings
False
#检查特点值是否不包含在列表中
banned_users=['andrew','carolina','david']
user='marie'
if user not in banned_users:
print(f'{
user.title()},you can post a response if you wish.')
Marie,you can post a response if you wish.
#布尔表达式
game_active=True
can_edit=False
#If
#if conditional_test:
# do something
age=19
if age>=18:
print('you are old enough to vote!')
you are old enough to vote!
age=19
if age>=18:
print('you are old enough to vote!')
print('Have you registered to vote yet?')
you are old enough to vote!
Have you registered to vote yet?
#If Else
age=17
if age>=18:
print('you are old enough to vote!')
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
age=12
if age<4:
print('Your admission cost is $0.')
elif age <18:
print('Your admission cost is $25.')
else:
print('Your admission cost is $40.')
Your admission cost is $25.
age=12
if age<4:
price=0
elif age <18:
price=25
else:
price=40
print(f'Your admission cost is ${
price}.')
Your admission cost is $25.
age=30
if age<4:
price=0
elif age <18:
price=25
elif age <65:
price=40
else:
price=20
print(f'Your admission cost is ${
price}.')
Your admission cost is $40.
age=30
if age<4:
price=0
elif age <18:
price=25
elif age <65:
price=40
else:
price=20
print(f'Your admission cost is ${
price}.')
Your admission cost is $40.
requested_toppings=['mushrooms','green peppers','extra cheese']
for requested_topping in requested_toppings:
print(f'Adding {
requested_topping}')
print('\nFinished making your pizza!')
Adding mushrooms
Adding green peppers
Adding extra cheese
Finished making your pizza!
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(f'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!
requested_toppings=[]
if requested_toppings:
for requested_topping in requested_toppings:
print(f'Adding {
requested_topping}.')
print('\nFinish making your pizza!')
else:
print('Are you sure you want to plan pizza?')
Are you sure you want to plan 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(f'Adding{
request_topping}.')
else:
print(f"sorry,we don't have {
requested_topping}." )
print('\nFinish making your pizza!')
Addingmushrooms.
sorry,we don’t have french fries.
Addingmushrooms.
Finish making your pizza!