python笔记10

今日内容

  1. 参数

  2. 作用域

  3. 函数嵌套

知识点回顾

函数基本结果

def func(name,age,email):
    # 函数体(保持缩进一致)
    a = 123
    print(a)
    return 1111#函数中,出现return后,后面的语句不再执行。
    b = 456
    print(b)

result = func(1,2,3)
    
# 函数默认返回值:None

参数

def func(n1,n2):
    print(n1,n2)
    
func(1,2)
func(1,[11,22,3])
func({'k1':'k'},[11,22,3])

# 严格按照顺序传参数:位置方式传参。
# 实际参数可以是任意类型。

返回值

  • 函数没有返回值,默认返回:None

  • 函数内部执行过程中遇到return,就终止。
    def func1():
    return "完成" # 函数每次执行到此,就返回;所以下面代码永远不执行。
    for i in range(10):
    print(i)
    func1()

    def func2():
        for i in range(10):
            print(i)
            return "完成"
        print(666)
    func2()
    
  • return 可以返回任意类型
    def func():
    return (1,2,3)

    v = func()
    print(v)
    
    # 特殊:返回元组
    def func():
        return 5,8,"alex"
    
    v = func()
    print(v)
    

昨日作业题

def func(data_list):
    val = data_list[1::2]
    return list(val)


v1 = func([1,2,3,4,5,5])
print(v1)
v2 = func((1,2,3,4,5,5))
print(v2)

# 其他类型可以通过强制转换为列表
# v1 = (1,2,3,4)
# v1 = {1,2,3,4}
# v1 = {'k1':'v1','k2':'v2'}
v1 = "asdfasdfasdf"
v2 = list(v1)
print(v2)	

def func(arg):
    if len(arg) > 5:
        return True
    else:
        return False
    
data = func([1111,22,3,42,12])
data = func((1111,22,3,42,12)

def func(a1,a2):
    if a1 > a2:
        return a1 
    else:
        return a2 
v1 = func(1,2)
v2 = func(11,2)


def func(a1,a2):
    return a1  if a1 > a2  else a2
v1 = func(1,2)
v2 = func(11,2)

def func(name,gender,age,edu):
    # template = "%s*%s*%s*%s" %(name,gender,age,edu,)
    # return template
    data_list = [name,gender,age,edu]
    return "*".join(data_list)
    

n1 = input('>')
n2 = input('>')
n3 = input('>')
n4 = input('>')
result = func(n1,n2,n3,n4)
print(result)

def func(max_range):
    result = [1,1]
    while True:

        val = result[-1] + result[-2]
        if val > max_range:
            break
        result.append(val)
    return result

v = func(100)
print(v)

   def func(name):
       with open('data.txt',mode='r',encoding='utf-8') as obj:
           # 方式一
           content = obj.read()
           flag = False 
           row_list = content.split('\n') # ['1|alex|123123','2|eric|rwerwe','3|wupeiqi|pppp']
           for row in row_list:
               v= row.split('|')
               if v[1] == name:
                   flag = True 
                   break
   	
       return flag 
                   
   
   func('alex')
   func('eric')
   
   # ############################################
   def func(name):
       with open('data.txt',mode='r',encoding='utf-8') as obj:
           # 方式一
           content = obj.read()
           row_list = content.split('\n') # ['1|alex|123123','2|eric|rwerwe','3|wupeiqi|pppp']
           for row in row_list:
               v= row.split('|')
               if v[1] == name:
                   return True 
                   
   
   v1 = func('alex')
   if v1:
       print('存在')
   else:
       print('不存在')

今日内容详细

  1. 参数

  2. 基本参数知识

    • 任意个数

    • 任意类型
      def func(a1,a2,a3):
      print(a1,a2,a3)

      func(1,"asdf",True)

  3. 位置传参(调用函数并传入参数)【执行】
    def func(a1,a2):
    print(a1,a2)

    func(1,3)
    
  4. 关键字传参【执行】
    def func(a1, a2):
    print(a1, a2)

    func(a2=99,a1=2)
    
    # 关键字传参数和位置传参可以混合使用(位置传入的参数 > 关键字参数在后 = 总参数个数)
    def func1(a1, a2, a3):
        print(a1, a2, a3)
    
    # func(1, 2, a3=9)
    # func(1, a2=2, a3=9)
    # func(a1=1, a2=2, a3=9)
    # func(a1=1, 2,3) # 错误
    
  5. 默认参数【定义】
    def func(a1,a2,a3=9,a4=10):
    print(a1,a2,a3,a4)

    func(11,22)
    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)
    
  6. 万能参数(打散)

    • *args

      • 可以接受任意个数的位置参数,并将参数转换成元组。

        • 调用函数无 *
          def func(*args):
          print(args)

          func(1,2,3,4)
          (1, 2, 3, 4)
          
        • 调用函数有 *
          def func(*args):
          print(args)

          func(*(1,2,3,4))
          func(*[1,2,3,4])
          (1, 2, 3, 4)
          (1, 2, 3, 4)
          
      • 只能用位置传参
        def func(*args):
        print(args)

        # func(1)
        # func(1,2)
        func(1,2) # args=(1, 2)
        func((11,22,33,44,55)) 
        # args=((11,22,33,44,55),),不带星号,相当于把当当成一个整体,当作元组的一个元素。
        func(*(11,22,33,44,55)) # args=(11,22,33,44,55)
        
        (1,)
        (1, 2)
        (1, 2)
        ((11, 22, 33, 44, 55),)
        (11, 22, 33, 44, 55)
        
    • **kwargs

      • 可以接受任意个数的关键字参数,并将参数转换成字典。

        • 调用函数无 **
          def func(**kwargs):
          print(kwargs)

          func(k1=1,k2="alex")
          {'k1': 1, 'k2': 'alex'}
          
        • 调用函数有**
          def func(kwargs):
          print(kwargs)
          func(
          ) # kwargs=

      • 只能用关键字传参

      • 综合应用:无敌 + 无敌 => 真无敌
        def func(*args,**kwargs):
        print(args,kwargs)

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

    参数相关重点:

    1. 定义函数
      def func1(a1,a2):
      pass

      def func2(a1,a2=None):
      pass

      def func3(*args,**kwargs):
      pass

    2. 调用函数
      位置参数 > 关键字参数

  7. 作用域

python中:

  • py文件:全局作用域

  • 函数:局部作用域
    a = 1
    def s1():
    x1 = 666
    print(x1)
    print(a)
    print(b)

    b = 2
    print(a)
    s1()
    a = 88888
    def s2():
        print(a,b)
        s1()
    
    s2()
    
    ======
    1
    666
    1
    2
    88888 2
    666
    88888
    2
    
  • 总结:

    • 一个函数是一个作用域
      def func():
      x = 9
      print(x)
      func()
      print(x)#全局变量无x定义,报错。

    • 作用域中查找数据规则:优先在自己的作用域找数据,自己没有就去 "父级" -> "父级" -> 直到全局,全部么有就报错。注意:父级作用域中的值到底是什么?
      x = 10
      def func():
      x = 9
      print(x)

      func()
      
    • 练习题:
      #!/usr/bin/env python
      # -- coding:utf-8 --

      # x = 10
      # def func():
      #     x = 9
      #     print(x)
      #     def x1():
      #         x = 999
      #         print(x)
      #
      # func()
      
      
      
      # x = 10
      # def func():
      #     x = 9
      #     print(x)
      #     def x1():
      #         x = 999
      #         print(x)
      #     x1()
      #
      # func()
      
      
      # x = 10
      # def func():
      #     x = 9
      #     print(x)
      #     def x1():
      #         x = 999
      #         print(x)
      #     print(x)
      #     x1()
      #
      # func()
      
      # x = 10
      # def func():
      #     x = 8
      #     print(x)
      #     def x1():
      #         x = 999
      #         print(x)
      #     x1()
      #     print(x)
      #
      # func()
      
      
      # x = 10
      # def func():
      #     x = 8
      #     print(x)
      #     def x1():
      #         print(x)
      #     x1()
      #     print(x)
      #
      # func()
      
      
      
      # x = 10
      # def func():
      #     x = 8
      #     print(x)
      #     def x1():
      #         print(x)
      #     x = 9
      #     x1()
      #     x = 10
      #     print(x)
      #
      # func()
      
      #
      # x = 10
      # def func():
      #     x = 8
      #     print(x)
      #     def x1():
      #         print(x)
      #
      #     x1()
      #     x = 9
      #     x1()
      #     x = 10
      #     print(x)
      #
      # func()
      
    • 子作用域中只能 找到父级中的值 ,默认无法重新为父级的变量进行赋值。(global/nonlocal可以强制做)
      # #####################
      name = 'oldboy'
      def func():
      name = 'alex' # 在自己作用域再创建一个这样的值。
      print(name)
      func()
      print(name)

      # #####################
      name = [1,2,43]
      def func():
          name.append(999)#列表为可变类型,可以修改。这里是修改,不是重新赋值。
          print(name)
      func()
      print(name)
      
      # ###################### 如果非要对全局的变量进行赋值
      # 示例一
      name = ["老男孩",'alex']
      def func():
          global name
          name = '我'
      func()
      print(name)
      # 示例一
      name = "老男孩"
      def func():
          name = 'alex'
          def inner():
              global name
              name = 999
          inner()
          print(name)
      func()
      print(name)
      
      
      name = "老男孩"
      def func():
          name = 'alex'
          def inner():
              global name
              name = 999
          inner()
          print(name)
      func()
      print(name)
      
      # ############################## nonlocal
      name = "老男孩"
      def func():
          name = 'alex'
          def inner():
              nonlocal name # 找到上一级的name
              name = 999
          inner()
          print(name)
      func()
      print(name)
      

总结

  • 参数
    • 调用(执行)函数时,传参:位置参数 > 关键字参数
    • 定义函数:
      • def func(a)
      • def func(a,b=None) # 对于默认值,如果是可变类型,----> 坑。
      • def func(*args,**kwargs)
  • 作用域
    • 函数为作用域
    • 自己 > 父级 > 父级 > 全局 【读/修改(可变)】
    • 重新赋值:
      • global
      • nonlocal

补充

  1. 全部变量以后必须全部是大写
    USER_LIST = [11,22,3]

    def func():
        name = 'asdf'
        USER_LIST.append(12)
        USER_LIST.append(name)
    
    func()
    print(USER_LIST)
    
posted @ 2020-02-04 21:04  cuiyongchao007  阅读(173)  评论(0编辑  收藏  举报