python 基础系列11-函数的构成

不念不忘少年蓝@ 2023-07-06 10:30 12阅读 0赞

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# python 基础系列11-函数的构成
    
    # 引入sys库
    import sys
    import copy
    from functools import reduce
    
    
    def func():
        print('aaaaaa')
        return
    
    
    def func2(x, y):
        print('bbbbb')
        return x + y
    
    
    def func3(x, y='xxx'):
        print(x, y)
        return x + y
    
    
    def func4(**war):
        print(war)
    
    
    def func5(*a):
        print(a)
    
    def func6(*a,**b):
        print(a,b)
    
    def func8(*a,**b):
        pass
    
    def func7(*a,**b):
        return 1,2
    
    if __name__ == '__main__':
        print(1)
        func()
        rs = func2(1, 2)
        print(rs)
    
        # 缺省参数
        rs3 = func3('as2')
        # rs3 = func3('as2','sssx')
    
        # 不定长参数
        func4(a=1, b=2, c=3, d=4)
        func5(1,2,3,4,5)
        func6(1,2,3,4,a=1, b=2, c=3, d=4) #常用用法
    
        #无返回值
        func7()
    
        #返回多个值,可以用变量接收
        var = func8()
        var1,var2 = func8()

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzMxODY2Nzkz_size_16_color_FFFFFF_t_70 3][]

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# python 基础系列 -作用域
    
    # 引入sys库
    import sys
    import copy
    from functools import reduce
    
    #全局变量
    a=11
    b=22
    
    def func():
        global a
        #局部变量
        a=3
        print(a)
        return 4
    
    mylist = [1,2,3]
    def func2(var):
        var[0] = 'a'
        #局部变量
        print(var)
        pass
    
    def func3(var):
        var1=var[:]
        var1[0] = 'a'
        #局部变量
        print(var1)
        pass
    if __name__ == '__main__':
        # 作用域
        print(a)
    
        #在函数内修改全局变量，使用 global 关联全局变量
        func()
        print(a) #这里的a值就发生了变化
    
        #函数内部修改参数--传引用 ,我们发现2者值一致 都为 ['a', 2, 3]
       # func2(mylist)
       # print(mylist)
    
        #为了解决上面的问题我们多加了一个赋值拷贝过程（注意是拷贝过程，而不是赋值）
        func3(mylist) #['a', 2, 3]
        print(mylist) #[1, 2, 3]

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzMxODY2Nzkz_size_16_color_FFFFFF_t_70 5][]

# python 基础系列-函数嵌套
    
    # 引入sys库
    import sys
    import copy
    from functools import reduce
    
    
    def fun1():
        print(1)
    
    def fun2():
        global fun1
        def fun1():
            print('aaaaa')
    
    
    def fun3():
        print(3)
    
    def fun4():
        print(4)
    
    
    if __name__ == '__main__':
    
        #函数嵌套
        fun2() 
        fun1() #要先申明这个函数

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzMxODY2Nzkz_size_16_color_FFFFFF_t_70 6][]

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# python 基础系列-匿名函数
    
    # 引入sys库
    import sys
    import copy
    from functools import reduce
    
    if __name__ == '__main__':
        print()
        #匿名函数一般做一些简单的函数
        f = lambda x:x*x
        rs= f(2)
        print(rs)
    
        #支持默认参数
        func=lambda  x,y =1 :x+y
        print(func(4))
    
        #用途：跳转表 举例子
        mylist = [lambda x:x*x,lambda x:x+1,lambda  x:x-1]
        for func in mylist:
            print(func(3)) #传参

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzMxODY2Nzkz_size_16_color_FFFFFF_t_70 8][]

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# python 基础系列 -递归
    
    # 引入sys库
    import sys
    import copy
    from functools import reduce
    
    
    def func(list):
        if list == []:
            print('列表为null')
            return 0
        return  list[0]+func(list[1:])
    
    def cost(money,day=0):
        if money <= 0 :
            print('没钱了,花了',day)
            return 0
        else:
            money = money // 2
            day +=1
            cost(money,day)
    def func2():
        print('a_1')
        func2()
    if __name__ == '__main__':
    
        #递归就是函数中包含对自身的调用：
        print(9/4)
        print(9//4)
        mylist= [1,2,3,4,5]
        sum = 0
        while mylist:
            sum += mylist[0]
            mylist = mylist[1:]
    
        print(sum)
    
        #递归求和方法：
        mylist2 = [1, 2, 3, 4, 5]
        print(func(mylist2))
    
        money = 10000
        #每天花一半的钱,求花多少天
        cost(money)
    
        #递归 效率高，但是内存消耗大 ，普通循环 内存小，效率稍低，py内部会设置一个最大值,会报错
        func2()

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