python进阶(5)--函数
文档目录：
一、函数体
二、实参与形参
三、返回值
四、举例：函数+while循环
五、举例：列表/元组/字典传递
六、模块与函数的导入
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1、定义删除
def green_user():
"""显示简单的问候语"""
print("hello world!")
green_user()
查看结果：
hello world！
2、函数传递信息
def green_user(username):
"""显示简单的问候语"""
print( f"Hello,{username.title()}!" )
green_user("Lucy")
查看结果：
Hello,Lucy!
1、概念
def green_user(username):
"""显示简单的问候语"""
print( f"Hello,{username.title()}!" )
green_user("Lucy")
形参：username
实参："Lucy"
2、位置实参，且支持多次调用
def describe_pet(animal_type,pet_name):
"""显示宠物的信息"""
print(f"I have a {animal_type}")
print(f"My {animal_type}'s name is {pet_name}")
describe_pet('dog','Mary')
describe_pet('cat','Little White')
查看结果：
I have a dog
My dog's name is Mary
I have a cat
My cat's name is Little White
3、实参中将名称和值关联起来
def describe_pet(animal_type,pet_name):
"""显示宠物的信息"""
print(f"I have a {animal_type}")
print(f"My {animal_type}'s name is {pet_name}")
describe_pet(animal_type='dog',pet_name='Mary')
查看结果：
I have a dog
My dog's name is Mary
4、默认值，需放在形参最后
def describe_pet(pet_name,animal_type='cat'):
"""显示宠物的信息"""
print(f"I have a {animal_type}")
print(f"My {animal_type}'s name is {pet_name}")
describe_pet(pet_name='Mary')
describe_pet('Big White')
查看结果：
I have a cat
My cat's name is Mary
I have a cat
My cat's name is Big White
1、返回简直值:return
def get_formatted_name(first_name,last_name):
"""返回全名，并且首字母大写"""
full_name=f"{first_name} {last_name}"
return full_name.title()
name=get_formatted_name("mike","jackson")
print(name)
查看结果：
Mike Jackson
2、实参可选
def get_formatted_name(first_name,last_name,middle_name=''):
"""返回全名，并且首字母大写"""
full_name=f"{first_name} {middle_name} {last_name}"
return full_name.title()
name1=get_formatted_name("mike","jackson",'midddd')
name2=get_formatted_name("mike","jackson")
print(name1)
print(name2)
3、返回字典
def build_person(first_name,last_name):
"""返回一个字段"""
persion={'first':first_name,'last':last_name}
return persion
dicttest1=build_person('xiao','long')
print(dicttest1)
查看结果：
{'first': 'xiao', 'last': 'long'}
def get_formatted_name(first_name,last_name):
"""返回全名，并且首字母大写"""
full_name=f"{first_name} {last_name}"
return full_name.title()
while True:
print("Please tell me your name:")
print("（enter 'q' at any time to quit）")
f_name=input("First name:")
if f_name=='q':
break
l_name=input("Last name:")
if l_name=='q':
break
formatted_name=get_formatted_name('mike','jackson')
print(f"\nhello,{formatted_name}!")
查看结果：
Please tell me your name:
（enter 'q' at any time to quit）
First name:mike
Last name:jackson
hello,Mike Jackson!
Please tell me your name:
（enter 'q' at any time to quit）
First name:tom
Last name:q
1、传递列表
def greet_users(names):
"""向列表中的每位用户发出简单的问候"""
for name in names:
msg=f"Hello,{name.title()}!"
print(msg)
username=['bk','anna','tom','mary']
greet_users(username)
查看结果：
Hello,Bk!
Hello,Anna!
Hello,Tom!
Hello,Mary!
2、在函数中修改列表
unconfirmed_users=['alice','brian','candace']
confirmed_users=[]
def confirmed(unconfirmed_users,confirmed_users):
while unconfirmed_users:
current_user = unconfirmed_users.pop()
print( f"Verfying users:{current_user.title()}" )
confirmed_users.append( current_user )
# 显示所有验证的用户
def print_confirmed_users(confirmed_users):
print( "\nThe following users have been confirmed!" )
for confirm_user in confirmed_users:
print( confirm_user.title() )
confirmed(unconfirmed_users,confirmed_users)
print_confirmed_users(confirmed_users)
print(unconfirmed_users)
查看结果：
Verfying users:Candace
Verfying users:Brian
Verfying users:Alice
The following users have been confirmed!
Candace
Brian
Alice
[]
3、优化：函数修改原列表
#将列表的副本传递给函数
unconfirmed_users=['alice','brian','candace']
confirmed_users=[]
def confirmed(unconfirmed_users,confirmed_users):
while unconfirmed_users:
current_user = unconfirmed_users.pop()
print( f"Verfying users:{current_user.title()}" )
confirmed_users.append( current_user )
# 显示所有验证的用户
def print_confirmed_users(confirmed_users):
print( "\nThe following users have been confirmed!" )
for confirm_user in confirmed_users:
print( confirm_user.title() )
confirmed(unconfirmed_users[:],confirmed_users)
print_confirmed_users(confirmed_users)
print(unconfirmed_users)
查看结果：原列表不会修改
Verfying users:Candace
Verfying users:Brian
Verfying users:Alice
The following users have been confirmed!
Candace
Brian
Alice
['alice', 'brian', 'candace']
4、传递任意数量的实参(元组)
#*号可以生成一个空元组，封装接收的所有值
def make_pizza(*toppings):
"""打印顾客点的所有配料"""
print(toppings)
make_pizza('pepperoni')
make_pizza('mushrooms','chesse','green peppers')
查看结果：
('pepperoni',)
('mushrooms', 'chesse', 'green peppers')
5、结合使用位置实参和任意数量实参
def make_pizza(size,*toppings):
"""打印顾客点的所有配料"""
print(f"Making a {size}-inch pizza with the folowing toppings")
for topping in toppings:
print(f'-{topping}')
make_pizza(16,'pepperoni')
make_pizza(12,'mushrooms','chesse','green peppers')
查看结果：
Making a 16-inch pizza with the folowing toppings
-pepperoni
Making a 12-inch pizza with the folowing toppings
-mushrooms
-chesse
-green peppers
6、使用任意数量的关键字实参（字典）
#**可以生成一个空字典
def build_profile(first,last,**user_info):
"""创建一个字典，其中包含有关用户的信息"""
user_info['first_name']=first
user_info['last_name']=last
return user_info
user_profile=build_profile('albert','master',location='princeton',field='physics',number=1)
print(user_profile)
查看运行结果：
{'location': 'princeton', 'field': 'physics', 'number': 1, 'first_name': 'albert', 'last_name': 'master'}
1、导入模块
import test04_function
test04_function.make_pizza(13,'prpperono')
test04_function.make_pizza(10,'prpperono','cheese','mushrooms')
查看结果：
Making a 13-inch pizza with the folowing toppings
-prpperono
Making a 10-inch pizza with the folowing toppings
-prpperono
-cheese
-mushrooms
2、导入特定的函数
from test04_function import make_pizza
make_pizza(10,'prpperono','cheese','mushrooms')
3、使用as给函数指定别名
from test04_function import make_pizza as mp
mp(10,'prpperono','cheese','mushrooms')
4、使用as给模块执行别名
import test04_function as pizza
pizza.make_pizza(10,'prpperono','cheese','mushrooms')
5、导入模块中的所有函数
from test04_function import *
