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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一、函数体

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!

二、实参与形参

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

三、返回值

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'}

四、举例：函数+while循环

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

五、举例：列表/元组/字典传递

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'}

六、模块与函数的导入

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 *