第8章 函数 1-3 节

# 8.1 定义函数
# greeter.py
def greet_user():
　　"""显示简单的问候语 """
　　print("hello!")

greet_user()

# 8.1.1 向函数传递信息

def greet_user(username):
　　"""显示简单的问候语"""
　　print("hello, " + username.title() + "!")

greet_user('star')

# 8.1.2 实参和形参
'''变量是形参，值是实参，实参是调用函数传递给函数的信息'''

 

# 8-1 消息：

def display_message():
　　"""显示信息"""
　　print("function")

display_message()

# 8-2 喜欢的图书
def favorite_book(bookname):
　　'''显示信息'''
　　print("one of my favorite book is " + bookname + ".")
# 区分形参与实参，不能相同，也不能混淆
favorite_book('alice in wonderland')

 

# 8.2.1 位置实参
'''实参关联形参，基于实参顺序，称为位置实参'''
def describe_pet(animal_type, pet_name):
　　'''显示宠物的信息'''
　　print("\ni have a " + animal_type + ".")
　　print("my " + animal_type + "'s name is " + pet_name.title() + ".")

'''实参顺序不正确，就会出现张冠李戴'''
describe_pet('hamster', 'harry')
describe_pet('dog', 'willie')

# 8.2.2 关键字实参
def describe_pet(animal_type, pet_name):
　　'''显示宠物信息'''
　　print("\ni have a " + animal_type + ".")
　　print("my " + animal_type + "'s name is " + pet_name.title() + ".")

'''定义关键字实参，顺序无关紧要'''
describe_pet(animal_type = 'hamster', pet_name = 'harry')
describe_pet(pet_name = 'harry', animal_type = 'hamster')

# 8.2.3 默认值
'''形参列表必须先列出没有默认值的形参，再列出有默认值的实参，正确解读位置实参。'''
def describe_pet(pet_name, animal_type = 'dog'):
　　'''显示宠物信息'''
　　print("\ni have a " + animal_type + ".")
　　print("my " + animal_type + "'s name is " + pet_name.title() + ".")
describe_pet(pet_name = 'willie')
describe_pet('willie')
describe_pet(pet_name = 'harry', animal_type = 'hamster')

# 8.2.4 等效的函数调用
'''一只名为willie的小狗'''
describe_pet(pet_name = 'willie')
describe_pet('willie')

'''一只名为harry的仓鼠'''
describe_pet('harry', 'hamster')
describe_pet(pet_name = 'harry', animal_type = 'hamster')
describe_pet(animal_type = 'hamster', pet_name = 'harry')

# 8.2.5 避免实参错误
'''提供实参或多或少不满足条件会导致不匹配错误'''

 

# 8-3 t恤
def make_shirt(shirt_size, shirt_text):
　　'''显示t恤尺码及印刷文字信息'''
　　print("\nmy t-shirt size is " + shirt_size + ".")
　　print(shirt_text.title() + " was printed on the t-shirt" + ".")

'''双引号里加单引号强调文字的特殊性'''
make_shirt("middle", "'faith'")

# 8-4 大号t恤
def make_shirt(shirt_size, shirt_text = "'i love python'"):
　　'''显示t恤尺码及印刷文字信息'''
　　print("\nmy t-shirt size is " + shirt_size + ".")
　　print(shirt_text + " was printed on the t-shirt" + ".")

make_shirt('large')
make_shirt('medium')
make_shirt('large', "'faith'")

# 8-5 城市
def describe_city(city_name, city_location = 'china'):
　　'''显示城市名称及所在国家'''
　　print("\n" + city_name.title() + " is in " + city_location.title())

describe_city('suzhou')
describe_city('nanjing')
describe_city('london','england')

 

# 8.3.1 返回简单值
def get_formatted_name(first_name, last_name):
　　'''返回整洁的姓名'''
　　full_name = first_name + ' ' + last_name
　　return full_name.title()

musician = get_formatted_name('jimi', 'hendrix')
print(musician)

# 8.3.2 让实参变成可选的
def get_formatted_name(first_name, middle_name, last_name):
　　'''返回整洁的名字'''
　　full_name = first_name + " " + middle_name + " " + last_name
　　return full_name.title()

musician = get_formatted_name('john', 'lee', 'hooker')
print(musician)

'''中间名变可选，设置默认空字符'''
def get_formatted_name(first_name, last_name, middle_name = ""):
　　'''返回整洁的名字'''
　　'''条件测试，返回函数调用行'''
　　if middle_name:
　　　　full_name = first_name + ' ' + middle_name + ' ' + last_name
　　else:
　　　　full_name = first_name + ' ' + last_name
　　return full_name.title()

musician = get_formatted_name('jimi', 'hendrix')
print(musician)

musician = get_formatted_name('john', 'hooker', 'lee')
print(musician)

# 8.3.3 返回字典
def build_person(first_name, last_name):
　　'''返回一个字典，其中包含有关一个人的信息'''
　　person = {'first': first_name, 'last': last_name}
　　return person

musician = build_person('jimi','hendrix')
print(musician)

'''扩展函数'''
def build_person(first_name, last_name, age = ''):
　　'''返回一个字典，其中包含有关一个人的信息'''
　　person = {'first': first_name, 'last': last_name}
　　if age:
　　# 为字典增加 键-值
　　　　person['age'] = age
　　return person

musician = build_person('jimi','hendrix', age = 27)
print(musician)

# 8.3.4 结合使用函数和while循环
# ~ def get_formatted_name(first_name, last_name):
# ~ '''返回整洁的名字'''
# ~ full_name = first_name + ' ' + last_name
# ~ return full_name.title()

# ~ # 这是一个无限循环
# ~ while true:
# ~ print("\nplease tell me your name:")
# ~ f_name = input("first name: ")
# ~ l_name = input("last name: ")

# ~ formatted_name = get_formatted_name(f_name,l_name)
# ~ print("\nhello, " + formatted_name + "!")

# 使用break 退出循环
def get_formatted_name(first_name, last_name):
　　'''返回整洁的名字'''
　　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 l_name == 'q':
　　　　break

formatted_name = get_formatted_name(f_name, l_name)
print("\nhello, " + formatted_name + "!")

 

# 8-6 城市名
def city_country(name, location):
　　'''返回城市名车及所在地'''
　　city_info = name + ' ' + location
　　return city_info.title()

city = city_country('sitiago' ,'chile')
print(city)
city = city_country('suzhou', 'china')
print(city)
city = city_country('london', 'england')
print(city)

# 8-7 专辑
def make_album(singer,album):
　　'''返回整洁的歌手信息'''
　　person = {'singer_name': singer, 'album_name': album}
　　return person

person_info = make_album('jay', '七里香')
print(person_info)
person_info = make_album('jay', '双节棍')
print(person_info)
person_info = make_album('jay', '青花瓷')
print(person_info)

# 8-8 用户的专辑
def make_album(singer,album):
　　'''返回整洁的歌手信息'''
　　person_info = singer + ' ' + album
　　return person_info.title()

while true:
　　print("\nplease tell me your favorite singer:")
　　print("(enter 'q' at any time to quit)")

　　singer_name = input("singer: ")
　　if singer_name == 'q':
　　　　break
　　album_name = input("album: ")
　　if album_name == 'q':
　　　　break

singer_info = make_album(singer_name, album_name)
print(singer_info)