Python学习之内置函数总结

In [1]: abs(-6)
Out[1]: 6

In [2]: abs(0)
Out[2]: 0

In [3]: abs(6.6)
Out[3]: 6.6

In [4]: result = all(['P' in 'Python', True, None])

In [5]: print(result)
# >>> 执行结果为 ：False

In [6]: result = all([True, 'test', 10, len('python')])

In [7]: print(result)
# >>> 执行结果为 ：True

In [8]: books = ['爬虫从入门到入狱', '面向监欲编程', '数据库开发从删库到跑路']

In [9]: for index, item in enumerate(books):
   ...:     print(index, item)
   ...: 

# >>> 执行结果如下：
# >>> 0 爬虫从入门到入狱
# >>> 1 面向监欲编程
# >>> 2 数据库开发从删库到跑路

username = input("请输入用户名:")
passWord = input("请输入密码:")


if __name__ == '__main__':
    print("用户名为：" + username)
    print("密码为：" + password)
    print("密码长度为：" + str(len(password)))
    print("密码的类型为：" + str(type(password)))

In [10]: name = 'Neo'

In [11]: isinstance(name, str)
Out[11]: True

In [12]: isinstance(name, int)
Out[12]: False

class Test(object):
    def __init__(self):
        self.a = 1
        self.b = 2
 
    def to_vars(self):
        return vars(self)
 
 
 
test = Test()
print test.to_vars()

class variable:
    x = 1
    y = 'a'
    z = True

test = variable() 

print(hasattr(test, 'x'))
print(hasattr(test, 'y'))
print(hasattr(test, 'z'))
print(hasattr(test, 'no'))

# >>> 执行结果如下：
# >>> True
# >>> True
# >>> True
# >>> False

class function_demo():
    name = 'demo'
    def run(self):
        return "hello function"


functiondemo = function_demo()
res = hasattr(functiondemo, 'age')  # 判断age属性是否存在，False
print(res)

setattr(functiondemo, 'age', 18 )  #对age属性进行赋值，无返回值

res1 = hasattr(functiondemo, 'age') #再次判断属性是否存在，True
print(res1)

# >>> 执行结果如下：
# >>> False
# >>> True

class function_demo():
    name = 'neo'
    def run(self):
        return "neo like run"


functiondemo = function_demo()
getattr(functiondemo, 'name')	# 获取name属性，存在就打印出来--- neo

getattr(functiondemo, "run")	# 获取run方法，存在打印出 方法的内存地址

getattr(functiondemo, "age", 18)	# 获取不存在的属性，返回一个默认值；这里的默认值为 '18'

getattr(functiondemo, "age")	# 获取不存在的属性，则会报错，如下图：

def any(iterable):
    for element in iterable:
        if element:
            return True
    return False

>>> a = [0, False, [], {}, ()]
>>> b = [0, False, [], {}, (), [[]]]
>>> c = {}
>>> any(a)
False
>>> any(b) # b 中的元素 [[]] 为 True 。
True
>>> any(c)
False