Python正课79 —— 内置方法

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# print(abs(-1))                 # 返回绝对值  # 1
#
# print(all([1, 2, 3, '']))      # 返回可迭代对象，有一个为0，None，空就是假的 # False
# print(all([1, 2, 3, ]))        # 返回可迭代对象    # True
#
# print(any([]))                 # False
#
# print(bin(111))                # 0b1101111
# print(oct(111))                # 0o157
# print(hex(111))                # 0x6f
#
# print(bool(''))                # False

# def func():
#     pass


# class Foo:
#     pass


# print(callable(Foo))            # True


# print(chr(65))                    # A
# print(ord('A'))                   # 65


# # ======= 掌握 =======
# class Foo:
#     pass
# obj = Foo()
# obj.xxx = 111

# print(dir(Foo))     # 可以查看可以.出来哪些属性     #['__class__', '__delattr__', '__dict__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__gt__', '__hash__', '__init__', '__init_subclass__', '__le__', '__lt__', '__module__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '__weakref__']

# print(dir(obj))     # 可以查看可以.出来哪些属性     #['__class__', '__delattr__', '__dict__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__gt__', '__hash__', '__init__', '__init_subclass__', '__le__', '__lt__', '__module__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '__weakref__', 'xxx']

# print(divmod(1000,4))         #总数据量，每一页的数据量
# 返回值：总页数，剩余数据       # (250, 0)

# # ======= 掌握 =======
# for i, v in enumerate(['a', 'b', 'c']):
#     print(i, v)
#
# #  0 a
# #  1 b
# #  2 c

# # ======= 掌握 =======
# res = eval('1+2')       # eval就是执行字符串中的表达式
# print(res)

# # ======= 掌握 =======
# 不可变集合
# s = frozenset({1, 2, 3})
# print(s)    # frozenset({1, 2, 3})

# hash(不可变类型)

# # ======= 掌握 =======
# isinstance判断一个对象是不是一个类的实例
# class Foo:
#     pass
#
# obj = Foo()
# print(isinstance(obj, Foo))     # True
# print(isinstance([], list))     # True  # 推荐
# print(type([]) is list)         # True  # 不推荐

# # 10 ** 2 % 3
# print(pow(10, 2, 3))        # 1

# # 了解
# print('aaa'.__repr__())  # 'aaa'

# # round 四舍五入
# print(round(1.545))    #  2
# print(round(1.445))    #  1

# # 切片
# s = slice(1, 4, 2)  # 不常用
# l1 = [1, 2, 3, 4]
# l2 = [3, 2, 5, 9, 6, 7]
#
# print(l1[1:4:2])  # [2, 4]
# print(l2[1:4:2])  # [2, 9]
# print(l1[s])    # [2, 4]
# print(l2[s])    #[2, 4]


# # ======= 掌握 =======
# # zip拉链函数 一个对一个，没有对应的就报错
# v1 = 'hello'
# v2 = [111, 222, 333, 444, 555]
# res = zip(v1, v2)
# print(list(res))    # [('h', 111), ('e', 222), ('l', 333), ('l', 444), ('o', 555)]


# # ======= 掌握 =======
# __import__()
import time
# import 'time'   # 报错
# 变量名 = __import__('time')
# x = __import__('time')
# x.sleep(3)



# # ======= 掌握 =======
# 下周：反射