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  • Python基础教程之 函数

# 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)


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