#向函数传递信息
def greet_user(username):
print("Hello, " + username.title() + "!")
Hello, Jesse!
#实参和形参
'''
username是一个形参——函数完成其工作所需的一项信息；
jesse是一个实参，调用函数时传递给函数的信息；
调用函数时，将要让函数使用的信息放在括号内greet_user('jesse')中
将实参jesse传递给了函数greet_user()，这个值被存储在username中
'''
#传递实参
'''
将函数调用中的每一个实参都关联到函数定义中的一个形参
基于实参的顺序——位置实参
'''
def describe_pet(animal_type, pet_name):
print("\nI have a pet " + animal_type + ".")
print("My " + animal_type + "'s name is " + pet_name + ".")
describe_pet('tugou','xiaohei')
I have a pet tugou.
My tugou's name is xiaohei.
#调用函数多次
def describe_pet(animal_type, pet_name):
print("\nI have a pet " + animal_type + ".")
print("My " + animal_type + "'s name is " + pet_name + ".")
describe_pet('tugou','xiaohei')
describe_pet('xiaomao','miao')
I have a pet tugou.
My tugou's name is xiaohei.
I have a pet xiaomao.
My xiaomao's name is miao.
#位置实参的顺序很重要
def describe_pet(animal_type, pet_name):
print("\nI have a pet " + animal_type + ".")
print("My " + animal_type + "'s name is " + pet_name + ".")
describe_pet('xiaohei','tugou')
I have a pet xiaohei.
My xiaohei's name is tugou.
#关键字实参
'''
关键字实参是传递给函数的名称-值对。无需考虑函数调用中的实参顺序。
'''
def describe_pet(animal_type, pet_name):
print("\nI have a pet " + animal_type + ".")
print("My " + animal_type + "'s name is " + pet_name + ".")
describe_pet(animal_type='tugou',pet_name='xiaohei')
I have a pet tugou.
My tugou's name is xiaohei.
#默认值
'''
可以给每个形参指定默认值，
'''
def describe_pet(pet_name, animal_type='dog'):
print("\nI have a pet " + animal_type + ".")
print("My " + animal_type + "'s name is " + pet_name + ".")
describe_pet(pet_name='xiaohei')
I have a pet dog.
My dog's name is xiaohei.
I have a pet dog.
My dog's name is xiaohei.
describe_pet(animal_type='xiaomao',pet_name='miao')
I have a pet xiaomao.
My xiaomao's name is miao.
#等效的函数调用
def describe_pet(pet_name, animal_type='dog'):
print("\nI have a pet " + animal_type + ".")
print("My " + animal_type + "'s name is " + pet_name + ".")
describe_pet(pet_name='xiaohei')
describe_pet('xiaohei')
describe_pet('miao','xiaomao')
describe_pet(animal_type='xiaomao',pet_name='miao')
describe_pet(pet_name='miao',animal_type='xiaomao')
I have a pet dog.
My dog's name is xiaohei.
I have a pet dog.
My dog's name is xiaohei.
I have a pet xiaomao.
My xiaomao's name is miao.
I have a pet xiaomao.
My xiaomao's name is miao.
I have a pet xiaomao.
My xiaomao's name is miao.
#避免实参错误
def describe_pet(pet_name, animal_type='dog'):
print("\nI have a pet " + animal_type + ".")
print("My " + animal_type + "'s name is " + pet_name + ".")
describe_pet()
---------------------------------------------------------------------------
TypeError Traceback (most recent call last)
<ipython-input-14-0f39ed801838> in <module>
4 print("My " + animal_type + "'s name is " + pet_name + ".")
5
----> 6 describe_pet()
TypeError: describe_pet() missing 1 required positional argument: 'pet_name'
#返回值
def get_formatted_name(first_name, last_name):
full_name = first_name + ' '+ last_name
return full_name.title()
musician = get_formatted_name('jimi', 'hendrix')
print(musician)
#让实参变成可选的
def get_formatted_name(first_name, middle_name, last_name):
full_name = first_name + ' '+ middle_name + ' ' + last_name
return full_name.title()
musician = get_formatted_name('john', 'lee', 'hooker')
print(musician)
def get_formatted_name(first_name, last_name, middle_name=''):
if middle_name:
full_name = first_name + ' ' + middle_name + ' ' + last_name
else:
full_name = first_name + ' '+ last_name
return full_name.title()
musician1 = get_formatted_name('jimi', 'hendrix')
musician2 = get_formatted_name('john', 'lee', 'hooker')
print(musician1)
print(musician2)
Jimi Hendrix
John Hooker Lee
#返回字典
def build_person(first_name, last_name):
person = {'first':first_name,'last':last_name}
return person
musician = build_person('jimi', 'hendrix')
print(musician)
{'first': 'jimi', 'last': 'hendrix'}
def build_person(first_name, last_name, age=''):
person = {'first':first_name,'last':last_name}
if age:
person['age']=age
return person
musician = build_person('jimi', 'hendrix', age=27)
print(musician)
{'first': 'jimi', 'last': 'hendrix', 'age': 27}
#结合使用函数和while循环
def get_formatted_name(first_name, last_name):
full_name = first_name + ' '+ last_name
return full_name.title()
while True:
print("\nPlease 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 f_name =='q':
break
formatted_name = get_formatted_name(f_name, l_name)
print("\nHello, " + formatted_name + "!")
Please tell me your name:
(enter 'q' at any time to quit)
First name:cui
Last name:jingjing
Hello, Cui Jingjing!
Please tell me your name:
(enter 'q' at any time to quit)
First name:wang
Last name:lulu
Hello, Wang Lulu!
Please tell me your name:
(enter 'q' at any time to quit)
First name:q
#传递列表
def greet_users(names):
for name in names:
msg = "Hello, " + name.title() + "!"
print(msg)
usernames = ['hannah', 'try', 'margot']
greet_users(usernames)
Hello, Hannah!
Hello, Try!
Hello, Margot!
def cui_family(names):
for name in names:
txt = "my name is " + name.title() + "."
print(txt)
a = ['cuirongsheng','zhoujianfeng','cuijingjing']
cui_family(a)
my name is Cuirongsheng.
my name is Zhoujianfeng.
my name is Cuijingjing.
#在函数中修改列表
'''
从列表unprinted_designs末尾删除一个设计，存储到中间变量current_design，显示一条消息，正在打印的设计，再将设计添加到新列表completed_models中
'''
unprinted_designs = ['iphones case','robot pendant','dodecahedron']
completed_models = []
while unprinted_designs:
current_design = unprinted_designs.pop()
print("printing model: " + current_design)
completed_models.append(current_design)
printing model: dodecahedron
printing model: robot pendant
printing model: iphones case
print("\nThe following models have been printed:")
for completed_model in completed_models:
print(completed_model)
The following models have been printed:
dodecahedron
robot pendant
iphones case
#第一个函数负责处理打印设计的工作，第二个概述打印了哪些设计
def print_models(unprinted_designs, completed_models):
while unprinted_designs:
current_design = unprinted_designs.pop()
print("printing model: " + current_design)
completed_models.append(current_design)
def show_completed_models(completed_models):
print("\nThe following models have been printed:")
for completed_model in completed_models:
print(completed_model)
unprinted_designs = ['iphones case','robot pendant','dodecahedron']
completed_models = []
print_models(unprinted_designs, completed_models)
show_completed_models(completed_models)
printing model: dodecahedron
printing model: robot pendant
printing model: iphones case
The following models have been printed:
dodecahedron
robot pendant
iphones case
#禁止函数修改列表
'''
保留未打印的设计列表，已备案
向函数传递的是副本，而不是原件
'''
function_name(list_name[:])
print_models(unprinted_designs[:], completed_models)
def print_models(unprinted_designs, completed_models):
while unprinted_designs:
current_design = unprinted_designs.pop()
print("printing model: " + current_design)
completed_models.append(current_design)
def show_completed_models(completed_models):
print("\nThe following models have been printed:")
for completed_model in completed_models:
print(completed_model)
unprinted_designs = ['iphones case','robot pendant','dodecahedron']
completed_models = []
print_models(unprinted_designs[:], completed_models)
show_completed_models(completed_models)
printing model: dodecahedron
printing model: robot pendant
printing model: iphones case
The following models have been printed:
dodecahedron
robot pendant
iphones case
['iphones case', 'robot pendant', 'dodecahedron']
#传递任意数量的实参
'''
预先不知道函数需要接受多少个实参
'''
def make_pizza(*toppings):
print(toppings)
make_pizza('pepperoni')
make_pizza('pepperoni', 'green peppers', 'extra cheese')
('pepperoni',)
('pepperoni', 'green peppers', 'extra cheese')
def make_pizza(*toppings):
print("\nMaking a pizza with the following toppings:")
for topping in toppings:
print("- " + topping)
make_pizza('pepperoni')
make_pizza('pepperoni', 'green peppers', 'extra cheese')
Making a pizza with the following toppings:
- pepperoni
Making a pizza with the following toppings:
- pepperoni
- green peppers
- extra cheese
#结合使用位置实参和任意数量实参，将接纳任意实参的形参放在最后
def make_pizza(size, *toppings):
print("\nMaking a " + str(size) + "-inch pizza with the following toppings:")
for topping in toppings:
print("- " + topping)
make_pizza(16, 'pepperoni')
make_pizza(12, 'pepperoni', 'green peppers', 'extra cheese')
Making a 16-inch pizza with the following toppings:
- pepperoni
Making a 12-inch pizza with the following toppings:
- pepperoni
- green peppers
- extra cheese
#使用任意数量的关键字实参，**user_info创建一个空字典，遍历字典中的键值对，并将每个键值对都加入到字典profile中
def build_profile(first, last, **user_info):
profile = {}
profile['first_name'] = first
profile['last_name'] = last
for key, value in user_info.items():
profile[key] = value
return profile
user_profile = build_profile('albert','einstein',location='princeton',field='physics')
print(user_profile)
{'first_name': 'albert', 'last_name': 'einstein', 'location': 'princeton', 'field': 'physics'}
#将函数存储在模块中
'''
代码块与主程序分离，通过函数指定描述性名称，让主程序容易理解；将函数存储在被称为模块的独立文件中，再将模块导入到主程序，import
'''
def make_pizza(size, *toppings):
print("\nMaking a " + str(size) + "-inch pizza with the following toppings:")
for topping in toppings:
print("- " + topping)
import pizza
pizza.make_pizza(16, 'pepperoni')
pizza.make_pizza(12, 'pepperoni', 'green peppers', 'extra cheese')
#使用as给函数指定别名
from pizza import make_pizza as mp
mp(16, 'pepperoni')
mp(12, 'pepperoni', 'green peppers', 'extra cheese')
#使用as给模块指定别名
import pizza as p
p.make_pizza(16, 'pepperoni')
p.make_pizza(12, 'pepperoni', 'green peppers', 'extra cheese')
#导入模块中的所有函数
'''
使用并非自己编写的大型模块时，最好不要使用这种导入方法，如果模块中有函数的名称与项目中使用的名称相同，会出意外
只导入自己需要的函数or导入整个模块并使用句点表示法
'''
from pizza import *
make_pizza(16, 'pepperoni')
make_pizza(12, 'pepperoni', 'green peppers', 'extra cheese')
#给形参指定默认值时，等号两边不要有空格
def function_name(parameter_0, parameter_1='default value')
#函数中调用关键字段
function_name(value_0, parameter_1='value')
