基本数据类型（数字&字符串）

1.python中的数据类型

　　python使用对象模型来存储数据，每一个数据类型都有一个内置的类，每新建一个数据，实际就是在初始化生成一个对象，即所有数据都是对象。
　　对象的三个特性

• 身份：内存地址，可以用id()获取

• 类型：决定了该对象可以保存什么类型值，可执行何种操作，需遵循什么规则，可用type()获取

• 值：对象保存的真实数据

　　注：我们在定义数据类型，只需这样：x＝1，内部生成数字类型1这一内存对象会自动触发，我们无需关心

　　数据类型

　　这里的字符串、数字、列表等都是数据类型,除此之外还有很多其他数据，处理不同的数据就需要定义不同的数据类型。

标准类型

数字

字符串

列表

元组

字典

其他类型

类型type

Null

文件

集合

函数／方法

类

模块 

 

 

 

 

 

 

 

 

 

 

2.标准数据类型

　2.1 数字

定义：a＝1
特性：
    1.只能存放一个值
    2.一经定义，不可更改
    3.直接访问
分类：整型，长整型，布尔，浮点，复数

2.1.1 整形

　　　　Python中的整数属于int类型，默认用十进制表示，此外也支持二进制，八进制,十六进制表示方式。

>>> 10
10            --------->默认十进制

>>> bin(10)
'0b1010'      --------->二进制表示整数时，数值前面要加上一个前缀“0b”
>>> oct(10)
'012'         --------->八进制表示整数时，数值前面要加上一个前缀“0”
>>> hex(10)
'0xa'         --------->十六进制表示整数时，数字前面要加上前缀0X或0x

　　python2.*与python3.*关于整型的区别：

python2.*
　　在32位机器上，整数的位数为32位，取值范围为-2**31～2**31-1，即-2147483648～2147483647
　　在64位系统上，整数的位数为64位，取值范围为-2**63～2**63-1，即-9223372036854775808～9223372036854775807
　　
python3.*
　　整行长度无限制

2.1.2 bool型

 　　　　bool型只有两个值：True和False

　　　　 之所以将bool值归类为数字，是因为我们也习惯用1表示True，0表示False。

2.1.3 float型

　　Python的浮点数就是数学中的小数。

　　在运算中，整数与浮点数运算的结果也是一个浮点数。

浮点数也就是小数，之所以称为浮点数，是因为按照科学记数法表示时，
一个浮点数的小数点位置是可变的，比如，1.23*109和12.3*108是相等的。
浮点数可以用数学写法，如1.23，3.14，-9.01，等等。但是对于很大或很小的浮点数，
就必须用科学计数法表示，把10用e替代，1.23*109就是1.23e9，或者12.3e8，0.000012
可以写成1.2e-5，等等。
整数和浮点数在计算机内部存储的方式是不同的，整数运算永远是精确的而浮点数运算则可能会有
四舍五入的误差。

2.1.4 comple型

　　复数由实数部分和虚数部分组成，一般形式为x＋yj，其中的x是复数的实数部分，y是复数的虚数部分，这里的x和y都是实数。
　　注，虚数部分的字母j大小写都可以。　　

>>> 1.3 + 2.5j == 1.3 + 2.5J
True

 

2.1.5 数字相关内建函数

　　      

2.2 字符串

2.2.1 定义与特性

　　字符串是一个有序的字符的集合，用于存储和表示基本的文本信息，' '或'' ''或''' '''中间包含的内容称之为字符串
　　特性：
　　　　1.只能存放一个值
　　　　2.不可变
　　　　3.按照从左到右的顺序定义字符集合，下标从0开始顺序访问，有序
　　补充：
　　　　1.字符串的单引号和双引号都无法取消特殊字符的含义，如果想让引号内所有字符均取消特殊意义，在引号前面加r，如name＝r'l\thf'
　　　　2.unicode字符串与r连用必需在r前面，如name＝ur'l\thf'

2.2.2 字符串的创建与常用操作

　　　　创建：

　　　　　　s = 'Hello,Eva！How are you?'

　　　　常用操作：

　　　　　　索引

　　　　　　切片

　　　　　　移除空白 strip

　　　　　　大小写转换upper/lower

　　　　　　替换replace

　　　　　　分割 split

　　　　　　包含 startswith/endswith/index/find

　　　　　　判断成分 isdigit/isalpha

　　　　　   计算长度 len函数

　　　　　

2.2.3  str字符串工厂函数

class str(object):
    """
    str(object='') -> str
    str(bytes_or_buffer[, encoding[, errors]]) -> str
Create a new string object from the given object. If encoding or

errors is specified, then the object must expose a data buffer

that will be decoded using the given encoding and error handler.

Otherwise, returns the result of object.str() (if defined)

or repr(object).

encoding defaults to sys.getdefaultencoding().

errors defaults to 'strict'.

"""

def capitalize(self): # real signature unknown; restored from doc

"""

首字母变大写

S.capitalize() -> str
Return a capitalized version of S, i.e. make the first character

have upper case and the rest lower case.

"""

return ""
def casefold(self): # real signature unknown; restored from doc

"""

S.casefold() -> str
Return a version of S suitable for caseless comparisons.

"""

return ""
def center(self, width, fillchar=None): # real signature unknown; restored from doc

"""

原来字符居中，不够用空格补全

S.center(width[, fillchar]) -> str
Return S centered in a string of length width. Padding is

done using the specified fill character (default is a space)

"""

return ""
def count(self, sub, start=None, end=None): # real signature unknown; restored from doc

"""

从一个范围内的统计某str出现次数

S.count(sub[, start[, end]]) -> int
Return the number of non-overlapping occurrences of substring sub in

string S[start:end].  Optional arguments start and end are

interpreted as in slice notation.

"""

return 0
def encode(self, encoding='utf-8', errors='strict'): # real signature unknown; restored from doc

"""

encode(encoding='utf-8',errors='strict')

以encoding指定编码格式编码，如果出错默认报一个ValueError，除非errors指定的是

ignore或replace
S.encode(encoding='utf-8', errors='strict') -> bytes
Encode S using the codec registered for encoding. Default encoding

is 'utf-8'. errors may be given to set a different error

handling scheme. Default is 'strict' meaning that encoding errors raise

a UnicodeEncodeError. Other possible values are 'ignore', 'replace' and

'xmlcharrefreplace' as well as any other name registered with

codecs.register_error that can handle UnicodeEncodeErrors.

"""

return b""
def endswith(self, suffix, start=None, end=None): # real signature unknown; restored from doc

"""

S.endswith(suffix[, start[, end]]) -> bool
Return True if S ends with the specified suffix, False otherwise.

With optional start, test S beginning at that position.

With optional end, stop comparing S at that position.

suffix can also be a tuple of strings to try.

"""

return False
def expandtabs(self, tabsize=8): # real signature unknown; restored from doc

"""

将字符串中包含的\t转换成tabsize个空格

S.expandtabs(tabsize=8) -> str
Return a copy of S where all tab characters are expanded using spaces.

If tabsize is not given, a tab size of 8 characters is assumed.

"""

return ""
def find(self, sub, start=None, end=None): # real signature unknown; restored from doc

"""

S.find(sub[, start[, end]]) -> int
Return the lowest index in S where substring sub is found,

such that sub is contained within S[start:end].  Optional

arguments start and end are interpreted as in slice notation.
Return -1 on failure.

"""

return 0
def format(self, *args, **kwargs): # known special case of str.format

"""

格式化输出

三种形式：

形式一.

>>> print('{0}{1}{0}'.format('a','b'))

aba
形式二：（必须一一对应）

>>> print('{}{}{}'.format('a','b'))

Traceback (most recent call last):

File "<input>", line 1, in <module>

IndexError: tuple index out of range

>>> print('{}{}'.format('a','b'))

ab
形式三：

>>> print('{name} {age}'.format(age=12,name='lhf'))

lhf 12
S.format(*args, **kwargs) -> str
Return a formatted version of S, using substitutions from args and kwargs.

The substitutions are identified by braces ('{' and '}').

"""

pass
def format_map(self, mapping): # real signature unknown; restored from doc

"""

与format区别

'{name}'.format(**dict(name='alex'))

'{name}'.format_map(dict(name='alex'))
S.format_map(mapping) -> str
Return a formatted version of S, using substitutions from mapping.

The substitutions are identified by braces ('{' and '}').

"""

return ""
def index(self, sub, start=None, end=None): # real signature unknown; restored from doc

"""

S.index(sub[, start[, end]]) -> int
Like S.find() but raise ValueError when the substring is not found.

"""

return 0
def isalnum(self): # real signature unknown; restored from doc

"""

至少一个字符，且都是字母或数字才返回True
S.isalnum() -> bool
Return True if all characters in S are alphanumeric

and there is at least one character in S, False otherwise.

"""

return False
def isalpha(self): # real signature unknown; restored from doc

"""

至少一个字符，且都是字母才返回True

S.isalpha() -> bool
Return True if all characters in S are alphabetic

and there is at least one character in S, False otherwise.

"""

return False
def isdecimal(self): # real signature unknown; restored from doc

"""

S.isdecimal() -> bool
Return True if there are only decimal characters in S,

False otherwise.

"""

return False
def isdigit(self): # real signature unknown; restored from doc

"""

S.isdigit() -> bool
Return True if all characters in S are digits

and there is at least one character in S, False otherwise.

"""

return False
def isidentifier(self): # real signature unknown; restored from doc

"""

字符串为关键字返回True
S.isidentifier() -> bool
Return True if S is a valid identifier according

to the language definition.
Use keyword.iskeyword() to test for reserved identifiers

such as "def" and "class".

"""

return False
def islower(self): # real signature unknown; restored from doc

"""

至少一个字符，且都是小写字母才返回True

S.islower() -> bool
Return True if all cased characters in S are lowercase and there is

at least one cased character in S, False otherwise.

"""

return False
def isnumeric(self): # real signature unknown; restored from doc

"""

S.isnumeric() -> bool
Return True if there are only numeric characters in S,

False otherwise.

"""

return False
def isprintable(self): # real signature unknown; restored from doc

"""

S.isprintable() -> bool
Return True if all characters in S are considered

printable in repr() or S is empty, False otherwise.

"""

return False
def isspace(self): # real signature unknown; restored from doc

"""

至少一个字符，且都是空格才返回True

S.isspace() -> bool
Return True if all characters in S are whitespace

and there is at least one character in S, False otherwise.

"""

return False
def istitle(self): # real signature unknown; restored from doc

"""

>>> a='Hello'

>>> a.istitle()

True

>>> a='HellP'

>>> a.istitle()

False
S.istitle() -> bool
Return True if S is a titlecased string and there is at least one

character in S, i.e. upper- and titlecase characters may only

follow uncased characters and lowercase characters only cased ones.

Return False otherwise.

"""

return False
def isupper(self): # real signature unknown; restored from doc

"""

S.isupper() -> bool
Return True if all cased characters in S are uppercase and there is

at least one cased character in S, False otherwise.

"""

return False
def join(self, iterable): # real signature unknown; restored from doc

"""

#对序列进行操作（分别使用' '与':'作为分隔符）

>>> seq1 = ['hello','good','boy','doiido']

>>> print ' '.join(seq1)

hello good boy doiido

>>> print ':'.join(seq1)

hello:good👦doiido
对字符串进行操作
>>> seq2 = "hello good boy doiido"

>>> print ':'.join(seq2)

h:e:l:l⭕ :g⭕o:d: 🅱️o:y: :d⭕i:i:d:o
对元组进行操作
>>> seq3 = ('hello','good','boy','doiido')

>>> print ':'.join(seq3)

hello:good👦doiido
对字典进行操作
>>> seq4 = {'hello':1,'good':2,'boy':3,'doiido':4}

>>> print ':'.join(seq4)

boy:good:doiido:hello
合并目录
>>> import os

>>> os.path.join('/hello/','good/boy/','doiido')

'/hello/good/boy/doiido'
S.join(iterable) -> str
Return a string which is the concatenation of the strings in the

iterable.  The separator between elements is S.

"""

return ""
def ljust(self, width, fillchar=None): # real signature unknown; restored from doc

"""

S.ljust(width[, fillchar]) -> str
Return S left-justified in a Unicode string of length width. Padding is

done using the specified fill character (default is a space).

"""

return ""
def lower(self): # real signature unknown; restored from doc

"""

S.lower() -> str
Return a copy of the string S converted to lowercase.

"""

return ""
def lstrip(self, chars=None): # real signature unknown; restored from doc

"""

S.lstrip([chars]) -> str
Return a copy of the string S with leading whitespace removed.

If chars is given and not None, remove characters in chars instead.

"""

return ""
def maketrans(self, *args, **kwargs): # real signature unknown

"""

Return a translation table usable for str.translate().
If there is only one argument, it must be a dictionary mapping Unicode

ordinals (integers) or characters to Unicode ordinals, strings or None.

Character keys will be then converted to ordinals.

If there are two arguments, they must be strings of equal length, and

in the resulting dictionary, each character in x will be mapped to the

character at the same position in y. If there is a third argument, it

must be a string, whose characters will be mapped to None in the result.

"""

pass
def partition(self, sep): # real signature unknown; restored from doc

"""

以sep为分割，将S分成head,sep,tail三部分
S.partition(sep) -> (head, sep, tail)
Search for the separator sep in S, and return the part before it,

the separator itself, and the part after it.  If the separator is not

found, return S and two empty strings.

"""

pass
def replace(self, old, new, count=None): # real signature unknown; restored from doc

"""

S.replace(old, new[, count]) -> str
Return a copy of S with all occurrences of substring

old replaced by new.  If the optional argument count is

given, only the first count occurrences are replaced.

"""

return ""
def rfind(self, sub, start=None, end=None): # real signature unknown; restored from doc

"""

S.rfind(sub[, start[, end]]) -> int
Return the highest index in S where substring sub is found,

such that sub is contained within S[start:end].  Optional

arguments start and end are interpreted as in slice notation.
Return -1 on failure.

"""

return 0
def rindex(self, sub, start=None, end=None): # real signature unknown; restored from doc

"""

S.rindex(sub[, start[, end]]) -> int
Like S.rfind() but raise ValueError when the substring is not found.

"""

return 0
def rjust(self, width, fillchar=None): # real signature unknown; restored from doc

"""

S.rjust(width[, fillchar]) -> str
Return S right-justified in a string of length width. Padding is

done using the specified fill character (default is a space).

"""

return ""
def rpartition(self, sep): # real signature unknown; restored from doc

"""

S.rpartition(sep) -> (head, sep, tail)
Search for the separator sep in S, starting at the end of S, and return

the part before it, the separator itself, and the part after it.  If the

separator is not found, return two empty strings and S.

"""

pass
def rsplit(self, sep=None, maxsplit=-1): # real signature unknown; restored from doc

"""

S.rsplit(sep=None, maxsplit=-1) -> list of strings
Return a list of the words in S, using sep as the

delimiter string, starting at the end of the string and

working to the front.  If maxsplit is given, at most maxsplit

splits are done. If sep is not specified, any whitespace string

is a separator.

"""

return []
def rstrip(self, chars=None): # real signature unknown; restored from doc

"""

S.rstrip([chars]) -> str
Return a copy of the string S with trailing whitespace removed.

If chars is given and not None, remove characters in chars instead.

"""

return ""
def split(self, sep=None, maxsplit=-1): # real signature unknown; restored from doc

"""

以sep为分割，将S切分成列表，与partition的区别在于切分结果不包含sep，

如果一个字符串中包含多个sep那么maxsplit为最多切分成几部分

>>> a='a,b c\nd\te'

>>> a.split()

['a,b', 'c', 'd', 'e']

S.split(sep=None, maxsplit=-1) -> list of strings
Return a list of the words in S, using sep as the

delimiter string.  If maxsplit is given, at most maxsplit

splits are done. If sep is not specified or is None, any

whitespace string is a separator and empty strings are

removed from the result.

"""

return []
def splitlines(self, keepends=None): # real signature unknown; restored from doc

"""

Python splitlines() 按照行('\r', '\r\n', \n')分隔，

返回一个包含各行作为元素的列表，如果参数 keepends 为 False，不包含换行符，如        果为 True，则保留换行符。

>>> x

'adsfasdf\nsadf\nasdf\nadf'

>>> x.splitlines()

['adsfasdf', 'sadf', 'asdf', 'adf']

>>> x.splitlines(True)

['adsfasdf\n', 'sadf\n', 'asdf\n', 'adf']
S.splitlines([keepends]) -> list of strings
Return a list of the lines in S, breaking at line boundaries.

Line breaks are not included in the resulting list unless keepends

is given and true.

"""

return []
def startswith(self, prefix, start=None, end=None): # real signature unknown; restored from doc

"""

S.startswith(prefix[, start[, end]]) -> bool
Return True if S starts with the specified prefix, False otherwise.

With optional start, test S beginning at that position.

With optional end, stop comparing S at that position.

prefix can also be a tuple of strings to try.

"""

return False
def strip(self, chars=None): # real signature unknown; restored from doc

"""

S.strip([chars]) -> str
Return a copy of the string S with leading and trailing

whitespace removed.

If chars is given and not None, remove characters in chars instead.

"""

return ""
def swapcase(self): # real signature unknown; restored from doc

"""

大小写反转

S.swapcase() -> str
Return a copy of S with uppercase characters converted to lowercase

and vice versa.

"""

return ""
def title(self): # real signature unknown; restored from doc

"""

S.title() -> str
Return a titlecased version of S, i.e. words start with title case

characters, all remaining cased characters have lower case.

"""

return ""
def translate(self, table): # real signature unknown; restored from doc

"""

table=str.maketrans('alex','big SB')
a='hello abc'

print(a.translate(table))
S.translate(table) -> str
Return a copy of the string S in which each character has been mapped

through the given translation table. The table must implement

lookup/indexing via getitem, for instance a dictionary or list,

mapping Unicode ordinals to Unicode ordinals, strings, or None. If

this operation raises LookupError, the character is left untouched.

Characters mapped to None are deleted.

"""

return ""
def upper(self): # real signature unknown; restored from doc

"""

S.upper() -> str
Return a copy of S converted to uppercase.

"""

return ""
def zfill(self, width): # real signature unknown; restored from doc

"""

原来字符右对齐，不够用0补齐
S.zfill(width) -> str
Pad a numeric string S with zeros on the left, to fill a field

of the specified width. The string S is never truncated.

"""

return ""
def add(self, *args, **kwargs): # real signature unknown

""" Return self+value. """

pass
def contains(self, *args, **kwargs): # real signature unknown

""" Return key in self. """

pass
def eq(self, *args, **kwargs): # real signature unknown

""" Return self==value. """

pass
def format(self, format_spec): # real signature unknown; restored from doc

"""

S.format(format_spec) -> str
Return a formatted version of S as described by format_spec.

"""

return ""
def getattribute(self, *args, **kwargs): # real signature unknown

""" Return getattr(self, name). """

pass
def getitem(self, *args, **kwargs): # real signature unknown

""" Return self[key]. """

pass
def getnewargs(self, *args, **kwargs): # real signature unknown

pass
def ge(self, *args, **kwargs): # real signature unknown

""" Return self>=value. """

pass
def gt(self, *args, **kwargs): # real signature unknown

""" Return self>value. """

pass
def hash(self, *args, **kwargs): # real signature unknown

""" Return hash(self). """

pass
def init(self, value='', encoding=None, errors='strict'): # known special case of str.init

"""

str(object='') -> str

str(bytes_or_buffer[, encoding[, errors]]) -> str
Create a new string object from the given object. If encoding or

errors is specified, then the object must expose a data buffer

that will be decoded using the given encoding and error handler.

Otherwise, returns the result of object.str() (if defined)

or repr(object).

encoding defaults to sys.getdefaultencoding().

errors defaults to 'strict'.

# (copied from class doc)

"""

pass
def iter(self, *args, **kwargs): # real signature unknown

""" Implement iter(self). """

pass
def len(self, *args, **kwargs): # real signature unknown

""" Return len(self). """

pass
def le(self, *args, **kwargs): # real signature unknown

""" Return self<=value. """

pass
def lt(self, *args, **kwargs): # real signature unknown

""" Return self<value. """

pass
def mod(self, *args, **kwargs): # real signature unknown

""" Return self%value. """

pass
def mul(self, args, **kwargs): # real signature unknown

""" Return selfvalue.n """

pass
@staticmethod # known case of new

def new(*args, **kwargs): # real signature unknown

""" Create and return a new object.  See help(type) for accurate signature. """

pass
def ne(self, *args, **kwargs): # real signature unknown

""" Return self!=value. """

pass
def repr(self, *args, **kwargs): # real signature unknown

""" Return repr(self). """

pass
def rmod(self, *args, **kwargs): # real signature unknown

""" Return value%self. """

pass
def rmul(self, args, **kwargs): # real signature unknown

""" Return selfvalue. """

pass
def sizeof(self): # real signature unknown; restored from doc

""" S.sizeof() -> size of S in memory, in bytes """

pass
def str(self, *args, **kwargs): # real signature unknown

""" Return str(self). """

pass