Python每日一谈｜No.3 :hello world,注释以及数据类型

print('Hellow World!')

In [84]: # 这是一个注释
    ...: print("Hello, World!")
    ...: '''
    ...: 这是多行注释，用三个单引号
    ...: 这是多行注释，用三个单引号
    ...: 这是多行注释，用三个单引号
    ...: '''
    ...: print("Hello, World!")
    ...: """
    ...: 这是多行注释，用三个双引号
    ...: 这是多行注释，用三个双引号
    ...: 这是多行注释，用三个双引号
    ...: """
    ...: print("Hello, World!")
      
Hello, World!
Hello, World!
Hello, World!

关于函数的几个方面应该在特定的小节中进行描述记录， 这几个方面如下文所述. 每节应该以一个标题行开始. 标题行以冒号结尾. 除标题行外, 节的其他内容应被缩进2个空格.

Args:
列出每个参数的名字, 并在名字后使用一个冒号和一个空格, 分隔对该参数的描述.如果描述太长超过了单行80字符,使用2或者4个空格的悬挂缩进(与文件其他部分保持一致). 描述应该包括所需的类型和含义. 如果一个函数接受*foo(可变长度参数列表)或者**bar (任意关键字参数), 应该详细列出*foo和**bar.

Returns: (或者 Yields: 用于生成器)
描述返回值的类型和语义. 如果函数返回None, 这一部分可以省略.

Raises:
列出与接口有关的所有异常.”

def fetch_smalltable_rows(table_handle: smalltable.Table,
                        keys: Sequence[Union[bytes, str]],
                        require_all_keys: bool = False,
) -> Mapping[bytes, Tuple[str]]:
    """
    Fetches rows from a Smalltable.

    Retrieves rows pertaining to the given keys from the Table instance
    represented by table_handle.  String keys will be UTF-8 encoded.

    Args:
        table_handle: An open smalltable.Table instance.
        keys: A sequence of strings representing the key of each table
        row to fetch.  String keys will be UTF-8 encoded.
        require_all_keys: Optional; If require_all_keys is True only
        rows with values set for all keys will be returned.

    Returns:
        A dict mapping keys to the corresponding table row data
        fetched. Each row is represented as a tuple of strings. For
        example:

        {b'Serak': ('Rigel VII', 'Preparer'),
        b'Zim': ('Irk', 'Invader'),
        b'Lrrr': ('Omicron Persei 8', 'Emperor')}

        Returned keys are always bytes.  If a key from the keys argument is
        missing from the dictionary, then that row was not found in the
        table (and require_all_keys must have been False).

    Raises:
        IOError: An error occurred accessing the smalltable.
    """

In [7]: a = 100          # 整型变量
   ...: b = 1000.0       # 浮点型变量
   ...: c = "runoob"     # 字符串

In [8]: type(a)
Out[8]: int

In [9]: type(b)
Out[9]: float

In [10]: type(c)
Out[10]: str
#当然，我们也可以更改变量类型
In [14]: d = str(a)

In [15]: type(d)
Out[15]: str

In [61]: print('Hellow\tWorld!\nNi\tHao.')
Hellow           World!
Ni           Hao.

In [62]: print(r'Hellow\tWorld!\nNi\tHao.')
Hellow\tWorld!\nNi\tHao.

In [68]: print(8 > 7)
    ...: print(8 << span=""> 7)
True
False
In [75]: a
Out[75]: 7

In [76]: a << span="">10 and a >5
Out[76]: True

In [65]: a = None
    ...: type(a)
Out[65]: NoneType
In [66]: print(a)
None

# a赋值为100
In [26]: a  = 100
  
 #查看内存地址
In [27]: id(a)
Out[27]: 4452845280
  
#查看数据类型
In [28]: type(a)
Out[28]: int

In [29]: b = a

In [30]: id(b)
Out[30]: 4452845280

In [31]: c = float(a)

In [32]: type(c)
Out[32]: float

In [33]: id(c)
Out[33]: 4485900944
  
In [52]: d = str(a)
  
In [54]: type(d)
Out[54]: str

In [53]: id(d)
Out[53]: 4485942256