python - basic knowledge of the function (a)

Process-oriented programming with a programming function

Up to now we have contacted, program written for: process-oriented programming [poor readability / reusability poor]

# 面向过程编程
user_input = input('请输入角色：')

if user_input == '管理员':
    import smtplib
    from email.mime.text import MIMEText
    from email.utils import formataddr

    msg = MIMEText('管理员，我想演男一号，你想怎么着都行。', 'plain', 'utf-8')
    msg['From'] = formataddr(["李邵奇", '[email protected]'])
    msg['To'] = formataddr(["管理员", '[email protected]'])
    msg['Subject'] = "情爱的导演"

    server = smtplib.SMTP("smtp.163.com", 25)
    server.login("[email protected]", "qq1105400511")
    server.sendmail('[email protected]', ['管理员', ], msg.as_string())
    server.quit()
elif user_input == '业务员':
    import smtplib
    from email.mime.text import MIMEText
    from email.utils import formataddr

    msg = MIMEText('业务员，我想演男一号，你想怎么着都行。', 'plain', 'utf-8')
    msg['From'] = formataddr(["李邵奇", '[email protected]'])
    msg['To'] = formataddr(["业务员", '业务员'])
    msg['Subject'] = "情爱的导演"

    server = smtplib.SMTP("smtp.163.com", 25)
    server.login("[email protected]", "qq1105400511")
    server.sendmail('[email protected]', ['业务员', ], msg.as_string())
    server.quit()
elif user_input == '老板':
    import smtplib
    from email.mime.text import MIMEText
    from email.utils import formataddr

    msg = MIMEText('老板，我想演男一号，你想怎么着都行。', 'plain', 'utf-8')
    msg['From'] = formataddr(["李邵奇", '[email protected]'])
    msg['To'] = formataddr(["老板", '老板邮箱'])
    msg['Subject'] = "情爱的导演"

    server = smtplib.SMTP("smtp.163.com", 25)
    server.login("[email protected]", "qq1105400511")
    server.sendmail('[email protected]', ['老板邮箱', ], msg.as_string())
    server.quit()

# 函数式编程
def send_email():
    import smtplib
    from email.mime.text import MIMEText
    from email.utils import formataddr

    msg = MIMEText('老板，我想演男一号，你想怎么着都行。', 'plain', 'utf-8')
    msg['From'] = formataddr(["李邵奇", '[email protected]'])
    msg['To'] = formataddr(["老板", '老板邮箱'])
    msg['Subject'] = "情爱的导演"

    server = smtplib.SMTP("smtp.163.com", 25)
    server.login("[email protected]", "qq1105400511")
    server.sendmail('[email protected]', ['老板邮箱', ], msg.as_string())
    server.quit()


user_input = input('请输入角色：')

if user_input == '管理员':
    send_email()
elif user_input == '业务员':
    send_email()
elif user_input == '老板':
    send_email()

For functional programming:

• Nature: the N lines of code to get away and gave him a name, can be found later by name and code execution.
• Scenes:
  • Repeat Code
  • Code particularly more than one screen may be selected by the function code divided

The basic structure function 2

# 函数的定义
def 函数名():   # 函数名的命名规范、建议与变量的一样
    # 函数内容 （缩进）
    pass

# 函数的执行
函数名()

def get_list_first_data():
    v = [11,22,33,44]
    print(v[0])

get_list_first_data()

# 注意：函数如果不被调用，则内部代码永远不会被执行。

# 假如：管理员/业务员/老板用的是同一个邮箱。
def send_email():
    print('发送邮件成功，假设有10含代码')


user_input = input('请输入角色：')

if user_input == '管理员':
    send_email()
elif user_input == '业务员':
    send_email()
elif user_input == '老板':
    send_email()

to sum up:

# 情况1
def f1():
    pass 
f1()

# 情况2
def f2(a1):
    pass 
f2(123)

# 情况3
def f3():
    return 1 
v1 = f3()

# 情况4
def f4(a1,a2):
    # ... 
    return 999
v2 = f4(1,7)

def show(name,age):
    """
    函数是干什么的...    # 必须注明函数
    :param name: 
    :param age: 
    :return: 
    """
    return None

Whether the data inside the function will be executed independently of each other confusion between the function and the function :()

• 1. The function is finished
• 2. Internal element is not used by another person ----> destroy the function performed by the amount of memory

Parameter 3 Functions

def get_list_first_data(aaa): # aaa叫形式参数(形参)
    v = [11,22,33,44]
    print(v[aaa])
    
get_list_first_data(1) # 2/2/1调用函数时传递叫：实际参数（实参）
get_list_first_data(2)
get_list_first_data(3)
get_list_first_data(0)

The exact order transmission parameters: parameter passing mode position

The actual parameters may be any type

# 假如：管理员/业务员/老板用的是同一个邮箱。
"""
def send_email(to):
    import smtplib
    from email.mime.text import MIMEText
    from email.utils import formataddr

    msg = MIMEText('导演，我想演男一号，你想怎么着都行。', 'plain', 'utf-8')
    msg['From'] = formataddr(["李邵奇", '[email protected]'])
    msg['To'] = formataddr(["导演", to])
    msg['Subject'] = "情爱的导演"

    server = smtplib.SMTP("smtp.163.com", 25)
    server.login("[email protected]", "qq1105400511")
    server.sendmail('[email protected]', [to, ], msg.as_string())
    server.quit()
"""
def send_email(to):
    template = "要给%s发送邮件" %(to,)
    print(template)
 

user_input = input('请输入角色：')

if user_input == '管理员':
    send_email('[email protected]')
elif user_input == '业务员':
    send_email('[email protected]')
elif user_input == '老板':
    send_email('[email protected]')

Exercises

# 1. 请写一个函数，函数计算列表 info = [11,22,33,44,55] 中所有元素的和。

def get_sum():
    info = [11,22,33,44,55]
    data = 0
    for item in info:
        data += item
    print(data)

get_sum()

# 2. 请写一个函数，函数计算列表中所有元素的和。

def get_list_sum(a1):
    data = 0
    for item in a1:
        data += item
    print(data)
    
get_list_sum([11,22,33])
get_list_sum([99,77,66])
v1 = [8712,123,123]
get_list_sum(v1)

# 3. 请写一个函数，函数将两个列表拼接起来。
def join_list(a1,a2):
    result = []
    result.extend(a1)
    result.extend(a2)
    print(result)
    
join_list([11,22,33],[55,66,77]

# 4. 计算一个列表的长度
def my_len(arg):
    count = 0
    for item in arg:
          count += 1
    print(count)

v = [11,22,33]
my_len(v)
len(v)

# 5. 发邮件的示例
          
def send_email(role,to):
    template = "要给%s%s发送邮件" %(role,to,)
    print(template)
 

user_input = input('请输入角色：')

if user_input == '管理员':
    send_email('管理员','[email protected]')
elif user_input == '业务员':
    send_email('业务员','[email protected]')
elif user_input == '老板':
    send_email('老板','[email protected]')

3.1 Katachisan

3.1.1 The basic parameters of knowledge

• It can be any number of parameters

• It can be any type

  def func(a1,a2,a3,a4):
    print(a1,a2,a3,a4)
  
  func(2,'name',[1,2,3],False)

3.1.2 default parameters

def func(a1,a2,a3=9,a4=10):   # 默认参数a3=9,a4=10
    print(a1,a2,a3,a4)

func(11,22)       # 不给a3,a4传值，则a3,a4等于默认参数
func(11,22,10)
func(11,22,10,100)
func(11,22,10,a4=100)
func(11,22,a3=10,a4=100)
func(11,a2=22,a3=10,a4=100)
func(a1=11,a2=22,a3=10,a4=100)

3.1.3 universal parameter (for break)

• *args

  Receiving position can be any number of arguments, and the parameters into tuples.

  1. Call function None *

  def func(*args):
    print(*args)
  
  func(1,2)   ==> (1,2)
  func(1,2,[12,3,4])   ==> (1,2,[12,3,4])
  func((11,22,33))   ==> ((11,22,33))  # 参数是一个元组，打印出来的效果是元组套元组。

  2. The calling function *

  def func(*args):
    print(args)
  
  func(*(11,22,33))   ==>(11,22,33)    # *是用来打散元组的，将元组中的每个元素作为参数。
  func(*[11,22,33])   ==>(11,22,33)    # *可以用来打散列表/元组 /字典/集合，只是循环内部元素

  3. The only parameter passing by position

  def func(*args):
      print(args)
  
  func(1)
  func(1,2)   # args=(1, 2)
  func((11,22,33,44,55))    # args=((11,22,33,44,55),)
  func(*(11,22,33,44,55))   # args=(11,22,33,44,55)

• ** kwargs

  Keywords can accept any number of arguments, and see the conversion parameters into a dictionary

  1. Call function None *

  def func(**kwargs):
    print(***kwargs)
  
  func(k=1)    **kwargs = {'k':1}
  func(k1=1,k2=3)   **kwargs = {'k1':1,'k2':3}

  2. The calling function *

  def func(**kwargs):
    print(kwargs)
  
  func(**{'k1':1,'k2':4,'k3':9})   **kwargs = {'k1':1,'k2':4,'k3':9}

  3. Use keywords can only pass parameters

• * Args / ** kwargs integrated use: Invincible Invincible + => true invincible

  def func(*args,**kwargs):
      print(args,kwargs)
  
  func(1,2,3,4,5,k1=2,k5=9,k19=999)     *arg = (1,2,3,4,5) **kwargs = {'k1':2,'k5':9,'k19':999}
  func(*[1,2,3],k1=2,k5=9,k19=999)      *arg = (1,2,3) **kwargs = {'k1':2,'k5':9,'k19':999}
  func(*[1,2,3],**{'k1':1,'k2':3})      *arg = (1,2,3) **kwargs = {'k1':1,'k2':3}
  func(111,222,*[1,2,3],k11='alex',**{'k1':1,'k2':3})  
  *arg = (111,222,1,2,3)   **kwargs = {'k11':'alex','k1':1,'k2':3}

3.2 arguments

3.2.1 Location pass parameters (call the function and pass parameters) (execution)

Call / time function is executed strictly in the order position of the incoming parameters

def func(a1,a2,a3):
    print(a1,a2,a3)
    
func(66,'alex',3)

3.2.2 key parameter passing (execution)

The key parameter is the parameter passing arguments to put to use in

def func(a1,a2):
    print(a1,a2)
    
func(a1=22,a2=8)

Pass pass parameters involved in key positions can be used in combination: the parameters to be passed in a position on the front, to be placed behind the key parameter passing, and finally equal to the total number of parameters

def func(a1,a2,a3):
    print(a1,a2,a3)
    
func(1,2,a3=3)
func(1,a2=2,a3=3)
func(a1=1,a2=2,a3=3)
func(a1=1,2,3)  # 是错误的

def func (): Custom open () function of the two built-in functions for python

matching len ()

3.3 Key parameters related to

• Defined Functions

  def func(a1,a2):
    pass
  
  def func(a1,a2=None):  # 对于默认值，不可变类型随便写，如果是可变类型（有坑）。
    pass
  
  def func(*args,**kwargs):
    pass

  For general use the default value of the function immutable type, variable type caution:

  If you want to set the default value is the empty list:

  # 不推荐使用（会有坑）：
  def func(data,value = [])
  pass
  
  推荐使用：
  def func(data ,value = None)
    if not value:
          value = []

  # 示例：
  def func（data,value = []
    value.append(data)
      return value
  
  v1 = func(1)   # v1 = [1]
  v2 = func(2,[11,22,33])   # v2 = [11,22,33,2]
  v3 = func(3)   # v3 = [1,3]

  Exercises:

  • def func (a, b = []) What trap?

    If you do not pass to the b parameter, the default is the same address

  • Look at the code written results

    def func(a,b=[]):
        b.append(a)
        return b
    
    l1 = func(1)
    l2 = func(2,[11,22])
    l3 = func(3)
    
    print(l1,l2,l3)   # [1,3]   [11,22,2]   [1,3]

  • Look at the code written results

    def func(a,b=[]):
        b.append(a)
        print(b)
    
    func(1)    # [1]
    func(2,[11,22,33])   # [11,22,33,2]
    func(3)   # [1,3]

• call function

  Front position parameter, the parameter after the keyword.