• 无聊。。。。。


    # __class__表示当前操作的对象是什么
    # 1、如何让b的对象实现a的shou方法
    # class A:
    #     def show(self):
    #         print("A-show")
    #
    # class B(A):
    #     def show(self):
    #         print("B-show")
    #
    # # obj = B()
    # # # print(obj.__class__)
    # # obj.__class__=A
    # # obj.show()
    
    
    
    #  2、这段代码怎么才能运行,(为了让对象的实例可以被直接调用,实现call方法)
    # class A(object):
    #     def __init__(self,a,b):
    #         self.__a = a
    #         self.__b = b
    #     def myprint(self):
    #         print("a=",self.__a,"b=",self.__b)
    #     # def __call__(self, num):
    #     #     print("call:",num + self.__a)
    #
    # # a = A(10,20)
    # # a.myprint()
    # #
    # # a(100)
    
    
    # 3、# __new__,和 __init__
    # class B:
    #     def fn(self):
    #         print("B-fn")
    #     def __init__(self):
    #         print("B-init")
    #
    # class A:
    #     def fn(self):
    #         print("A-fn")
    #     def __new__(cls, a):
    #         print("new",a)
    #         if a > 10:
    #             return super(A,cls).__new__(cls)
    #         return B
    #     def __init__(self,a):
    #         print("init",a)
    #
    # # a1 = A(5)
    # # a1.fn(1)
    # # a2 = A(20)
    # # a2.fn()
    
    
    # 4、list or dict
    # ls = [1,2,3,4]
    # list1 = [i for i in ls if i>2]
    # print(list1)         #[3, 4]
    #
    # list2 = [i*2 for i in ls if i>2]
    # print(list2)         #[6, 8]
    #
    # dic1 = {x:x**2 for x in (2,4,6)}
    # print(dic1)         #{2: 4, 4: 16, 6: 36}
    #
    # dic2 = {x:'item'+str(x**2) for x in (2,4,6)}
    # print(dic2)        #{2: 'item4', 4: 'item16', 6: 'item36'}
    #
    # set1 = {x for x in 'hello world' if x not in 'low level'}
    # print(set1)        #{'d', 'h', 'r'}
    
    
    # 6、全局or局部
    # num = 9
    # def f1():
    #     global num
    #     num = 20
    #     # print(num)
    # def f2():
    #     print(num)
    # f2()
    # f1()
    # f2()
    
    
    # class A:
    #     def __init__(self,a,b):
    #         self.a1 = a
    #         self.b1 = b
    #         print("init")
    #     def mydefault(self):
    #         print("default")
    #     def __getattr__(self, item):
    #         print("getattr")
    #         return self.mydefault()
    #
    # a1 = A(10,20)
    # a1.fn1()
    
    
    
    # __all__ = ["mod2","mod1"]   #  卸载iniit里,只导入这两个模块
    #
    # def mulby(num):
    #     def gn(val):
    #         return num * val
    #     return gn
    #
    # zw = mulby(7)
    # print(zw(6))
    
    
    def strtest(num):
        str1 = "first"
        for i in range(num):
            str1 +="x"
        return str1
    # python的str是个不可变对象,每次迭代,都会生成新的str对象来存储新的字符串,num越大,创建的str对象越多,内存消耗越大。
    
    
    # numbers = [x*x for x in range(20) if x % 3 == 0]
    # numbers = {x * x for x in range(0, 20) if x % 3 == 0}
    # numbers = {x: x * x for x in range(0, 20) if x % 3 == 0}
    
    a = "I love python"
    reverse_a = a[::-1]
    print(reverse_a)
    
    cities = ["beijin","tianjin","shenzhegn"]
    for index,city in enumerate(cities,1):
        print(index,":",city)
    def fn(x):
        return x * x
    map(fn,[1,2,3])
    map(lambda x:x*x,[1,2,3])
    
    l = [x for x in range(10)]     # 列表
    print(l)
    
    g = (x for x in range(10))     #生成器
    print(g)
    
    # 统计一篇文章里出现的某个单词的次数
    from collections import Counter
    import re
    def computercount(word):
        wordlist = Counter(re.split("W+",word))
        return wordlist
    
    x = "wo zhi dao wo shi keyi zuo de wo shi ni da ye"
    # print(computercount(x))
    
    # 函数返回多个值
    def fx():
        error_code = 0
        error_desc = "success"
        return error_code,error_desc
    code,desc = fx()
    print(code,desc)
    
    # 找出列表中出现次数最多的数
    nums = [1,1,1,1,1,2,3,3,4,5,4,6,4,7]
    print(max(set(nums),key=nums.count))
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  • 原文地址:https://www.cnblogs.com/52-qq/p/8608370.html
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