1、传递实参
1.1 位置实参
def describe_pet(animal_type,pet_name):
print("\nI have a"+animal_type+".")
print("My "+animal_type+"'s name is "+pet_name.title()+".")
describe_pet('hamster','harry')
-->I have ahamster.
My hamster's name is Harry.
注意：函数调用中实参的顺序与函数定义中形参的顺序一致
1.2 关键字实参
describe_pet(animal_type='hamster',pet_name='harry')
describe_pet(pet_name='harry',animal_type='hamster')
-->I have ahamster.
My hamster's name is Harry.
I have ahamster.
My hamster's name is Harry.
注意：使用关键字实参时，务必准确地指定函数定义中的形参名
1.3 默认值
def describe_pet(pet_name,animal_type='dog'):
print("\nI have a "+animal_type+".")
print("My "+animal_type+"'s name is "+pet_name.title()+".")
describe_pet(pet_name='willie')
-->I have a dog.
My dog's name is Willie.
注意：在调用函数中给形参提供了实参时，Python将使用指定的实参值；否则，将使用形参的默认值。在使用默认值时，在形参列表中必须先列出没有默认值的形参，再列出有默认值的实参，这让python能正确解读位置实参。
2、返回值
2.1 返回简单值
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)
-->Jimi Hendrix
2.2 让实参变得可选
def get_formatted_name(first_name,last_name,middle_name=''): //先让中间名字形参默认为空
if middle_name: //用if语句判断
full_name=first_name+" "+middle_name+" "+last_name //有中间名字时加上实参
else:
full_name=first_name+" "+last_name
return full_name.title()
musician=get_formatted_name('jimi','hendrix2')
print(musician)
musician=get_formatted_name('john','hooker','lee')
print(musician)
-->Jimi Hendrix2
John Lee Hooker
2.3 返回字典
def build_person(first_name,last_name):
person={'first':first_name,'last':last_name}
return person
musician=build_person('tom','smith')
print(musician)
-->{'first': 'tom', 'last': 'smith'}
3、传递列表
def greet_users(names): //形参是一个列表
for name in names:
msg="Hello, "+name.title()+"!"
print(msg)
usernames=['hahana','ty','margot']
greet_users(usernames)
-->Hello, Hahana!
Hello, Ty!
Hello, Margot!
3.1 在函数中修改列表
def print_models(unprinted_designs,completed_models):
while unprinted_designs:
current_design=unprinted_designs.pop()
print("Printiing 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=['iphone case','robot pendant','dodecahedron']
completed_models=[]
print_models(unprinted_designs,completed_models)
show_completed_models(completed_models)
-->Printiing model: dodecahedron //每个函数只负责一项具体的工作
Printiing model: robot pendant
Printiing model: iphone case
The following models have been printed:
dodecahedron
robot pendant
iphone case
4、传递任意数量的实参
def make_pizza(*toppings): //形参*toppings中的星号让Python创建一个名为toppings的空元组
print(toppings)
make_pizza('pepperoni')
make_pizza('mushrooms','green peppers','extra cheese')
-->('pepperoni',)
('mushrooms', 'green peppers', 'extra cheese')
4.1 结合使用位置参数和任意数量实参
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,'mushrooms','green peppers','extra cheese')
-->Making a 16-inch pizza with the following toppings:
-pepperoni
Making a 12-inch pizza with the following toppings:
-mushrooms
-green peppers
-extra cheese
4.2 使用任意数量的关键字实参
def build_profile(first,last,**user_info): #形参**user_info中的两个星号让Python创建一个空字典，须放于形参最后位置
profile={}
profile['first-name']=first
profile['last-name']=last
for k,v in user_info.items():
profile[k]=v
return profile
a=build_profile('albert','einstein',location='princeton',field='physics')
print(a)
-->{'first-name': 'albert', 'last-name': 'einstein', 'location': 'princeton', 'field': 'physics'}
5、将函数存储在模块中
5.1 导入整个模块
pizza.py
def make_pizza(size,*toppings):
print("\nMaking a "+str(size)+"-inch pizza with the following toppings:")
for topping in toppings:
print("-"+topping)
同目录下making_pizza.py
import pizza //引用pizza则pizza.py中所有函数都能用
pizza.make_pizza(16,'pepperoni')
pizza.make_pizza(12,'mushrooms','green peppers','extra cheese')
5.2 导入特定的函数
from module_name import function_name
通过用逗号分隔函数名，导入任意数量的函数
from module_name import function_0，function_1,function_2
5.3 使用as给函数指定别名
from module_name import function_name as fn
5.4 使用as给模块指定别名
import module_name as mn
5.5 导入模块中的所有函数
from module_name import * #星号（*）运算符可导入模块中的所有函数
注意：所有的import语句都应放在文件开头，唯一例外的情形是，在文件开头使用了注释来描述整个程序