如何查看字符串有哪些内置方法？
我们可以先创建一个类型为字符串的变量，然后查看该变量的类型。
然后用dir()方法查看字符串的内置方法有哪些。最后可以用help()查看各个内置方法的用法
|
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>>> string=
'hello'
>>>
type
(string)
<
type
'str'
>
>>>
dir
(str)
[
'__add__'
,
'__class__'
,
'__contains__'
,
'__delattr__'
,
'__doc__'
,
'__eq__'
,
'__format__'
,
'__ge__'
,
'__getattribute__'
,
'__getitem__'
,
'__getnewargs__'
,
'__getslice__'
,
'__gt__'
,
'__hash__'
,
'__init__'
,
'__le__'
,
'__len__'
,
'__lt__'
,
'__mod__'
,
'__mul__'
,
'__ne__'
,
'__new__'
,
'__reduce__'
,
'__reduce_ex__'
,
'__repr__'
,
'__rmod__'
,
'__rmul__'
,
'__setattr__'
,
'__sizeof__'
,
'__str__'
,
'__subclasshook__'
,
'_formatter_field_name_split'
,
'_formatter_parser'
,
'capitalize'
,
'center'
,
'count'
,
'decode'
,
'encode'
,
'endswith'
,
'expandtabs'
,
'find'
,
'format'
,
'index'
,
'isalnum'
,
'isalpha'
,
'isdigit'
,
'islower'
,
'isspace'
,
'istitle'
,
'isupper'
,
'join'
,
'ljust'
,
'lower'
,
'lstrip'
,
'partition'
,
'replace'
,
'rfind'
,
'rindex'
,
'rjust'
,
'rpartition'
,
'rsplit'
,
'rstrip'
,
'split'
,
'splitlines'
,
'startswith'
,
'strip'
,
'swapcase'
,
'title'
,
'translate'
,
'upper'
,
'zfill'
]
|
以上就是字符串所有的内置方法。
常用的字符串方法：
首字母大写
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>>> string=
"asdf"
>>> string.capitalize()
'Asdf'
|
center(长度，填充符号)：
输出指定长度的字符串，并且将目标字符串居中，两边以指定的符号填充
|
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|
string=
"asdf"
>>> string.center(10,
'*'
)
‘***asdf***'
|
count(‘字符串’，开始下标，结束下标) ：
查看子序列的个数，或者说查看某个字符的个数
|
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|
>>> name=
"asdfsdfsdfasdf"
>>> name.count(
's'
)
4
>>> name.count(
's'
,0,9)
3
|
expandtabs(空格个数)：
将tab转换成空格，可以指定转换成多格式空格，默认一个tab转换成8个空格
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>>> name=
'ze\tng'
>>> name.expandtabs()
'ze ng'
>>> name.expandtabs(1)
'ze ng’
|
find() :
寻找第一个被匹配到的子序列的下标，如果没有找到，则返回-1
|
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|
>>> string
'asdf'
>>> string.
find
(
's'
)
1
>>> string.
find
(
'e'
)
-1
|
format() :
字符串格式化
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>>> string =
"I am {0},age {1}"
>>> string.
format
(
'zenge'
,28)
'I am zenge,age 28'
还可以这样：
>>> string =
"I am {ss},age {dd}"
>>> string.
format
(ss=
'zenge'
,
dd
=28)
'I am zenge,age 28’
##第二种方法相比较于第一种方法好处是，传值的时候不需要按照顺序传
|
列表传参
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>>> list=[‘zeng',28]
>>> name=
"I am {0},age {1}"
>>> name.
format
(*list)
'I am zeng,age 28’
|
字典传参
|
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>>> dict={
'ss'
:
'zeng'
,
'dd'
:28}
>>> name=
"I am {ss},age {dd}"
>>> name.
format
(**dict)
'I am zeng,age 28'
|
index():
查找指定字符的下标，和find差不多，区别在于如果要查找的字符不存在，那么find返回-1，而index则会报错
|
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|
>>> string =
"asddfasd"
>>> string.index(d)
>>> string.index(
'd'
)
2
|
isalnum()：
检查字符串是否为字母和数字，返回值为布尔型
|
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>>> name=
"曾"
>>> name.isalnum()
False
|
islower():
检查字符串是否全都是小写，返回值为布尔型，对应的是isupper()
|
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>>> name=
"asdfasA"
>>> name.islower()
False
|
isdigit():
检查字符串是否全部为数字
|
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>>> num=
'12323'
>>> num.isdigit()
True
>>> num=
'123234hehe'
>>> num.isdigit()
False
|
isspace()：
检查字符串是否全部为空格
|
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>>> name =
' '
>>> name.isspace()
True
>>> name =
' 1'
>>> name.isspace()
False
|
istitle() :
检查字符串是否为标题（标题的特点是首字母大写）
|
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>>> name=
"alex sb"
>>> name.istitle()
False
|
titie() :
将字符串转换成标题, 标题格式就是首字母大写
|
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>>> name=
"alex sb"
>>> name.title()
'Alex Sb’
|
join() :
将列表中的元素用符号连接起来组成字符串
|
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3
|
>>> list=[
"zeng"
,
'28'
]
>>>
'_'
.
join
(list)
'zeng_28'
|
ljust(宽度，填充符号) :
内容左对齐 右对齐为rjust()，与center()对应
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>>> name=“asdasd"
>>> name.ljust(20,
'*'
)
'asdasd**************'
|
upper() ：
字符串由小写变成大写, 与之相反的是lower() ,大写变成小写
|
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>>> name
'asdasd'
>>> name.upper()
'ASDASD'
|
swapcase() :
大小写转换，大写的转换成小写，小写的转换成大写
|
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|
>>> name=
"aaaBBB"
>>> name.swapcase()
'AAAbbb'
|
partition() ：
将字符串按照指定的字符或者符号分割成前中后三部分
|
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3
|
>>> name=
"Hello world"
>>> name.partition(
'll'
)
(
'He'
,
'll'
, 'o world’)
|
replace(old，new)：
替换 ,注意字符中所有满足条件的都会被替换
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|
'Hello world'
>>> name.replace(
'll'
,
'LL'
)
'HeLLo world'
|
split()
将字符串以某个字符分割，分割后的结果为列表
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|
>>> name =
"hello,zeng"
>>> name.
split
(
','
)
[
'hello'
,
'zeng'
]
|
strip()
删除字符串中指定的字符，例如删除空格，rstrip()方法是删除字符串右边的指定字符，lstrip()方法是删除字符串左边的指定字符
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>>> name =
' zeng '
>>> name.strip(
''
)
' zeng '
>>> name.strip(
' '
)
'zeng'
>>> name.rstrip(
' '
)
' zeng'
>>> name.lstrip(
' '
)
'zeng '
|
使用help()方法查看字符串所有内置方法的详细信息和用法
|
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|
| Methods defined here:
|
| __add__(...)
| x.__add__(y) <==> x+y
|
| __contains__(...)
| x.__contains__(y) <==> y
in
x
|
| __eq__(...)
| x.__eq__(y) <==> x==y
|
| __format__(...)
| S.__format__(format_spec) -> string
|
| Return a formatted version of S as described by format_spec.
|
| __ge__(...)
| x.__ge__(y) <==> x>=y
|
| __getattribute__(...)
| x.__getattribute__(
'name'
) <==> x.name
|
| __getitem__(...)
| x.__getitem__(y) <==> x[y]
|
| __getnewargs__(...)
|
| __getslice__(...)
| x.__getslice__(i, j) <==> x[i:j]
|
| Use of negative indices is not supported.
|
| __gt__(...)
| x.__gt__(y) <==> x>y
|
| __hash__(...)
| x.__hash__() <==>
hash
(x)
|
| __le__(...)
| x.__le__(y) <==> x<=y
|
| __len__(...)
| x.__len__() <==> len(x)
|
| __lt__(...)
| x.__lt__(y) <==> x<y
|
| __mod__(...)
| x.__mod__(y) <==> x%y
|
| __mul__(...)
| x.__mul__(n) <==> x*n
|
| __ne__(...)
| x.__ne__(y) <==> x!=y
|
| __repr__(...)
| x.__repr__() <==> repr(x)
|
| __rmod__(...)
| x.__rmod__(y) <==> y%x
|
| __rmul__(...)
| x.__rmul__(n) <==> n*x
|
| __sizeof__(...)
| S.__sizeof__() -> size of S
in
memory,
in
bytes
|
| __str__(...)
| x.__str__() <==> str(x)
|
| capitalize(...)
| S.capitalize() -> string
|
| Return a copy of the string S with only its first character
| capitalized.
|
| center(...)
| S.center(width[, fillchar]) -> string
|
| Return S centered
in
a string of length width. Padding is
|
done
using the specified fill character (default is a space)
|
| count(...)
| 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.
|
| decode(...)
| S.decode([encoding[,errors]]) -> object
|
| Decodes S using the codec registered
for
encoding. encoding defaults
| to the default encoding. errors may be given to
set
a different error
| handling scheme. Default is
'strict'
meaning that encoding errors raise
| a UnicodeDecodeError. Other possible values are
'ignore'
and
'replace'
| as well as any other name registered with codecs.register_error that is
| able to handle UnicodeDecodeErrors.
|
| encode(...)
| S.encode([encoding[,errors]]) -> object
|
| Encodes S using the codec registered
for
encoding. encoding defaults
| to the default encoding. 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 is able to handle UnicodeEncodeErrors.
|
| endswith(...)
| 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.
|
| expandtabs(...)
| S.expandtabs([tabsize]) -> string
|
| 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.
|
|
find
(...)
| 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.
|
|
format
(...)
| S.
format
(*args, **kwargs) -> string
|
| Return a formatted version of S, using substitutions from args and kwargs.
| The substitutions are identified by braces (
'{'
and
'}'
).
|
| index(...)
| S.index(sub [,start [,end]]) -> int
|
| Like S.
find
() but raise ValueError when the substring is not found.
|
| isalnum(...)
| S.isalnum() -> bool
|
| Return True
if
all characters
in
S are alphanumeric
| and there is at least one character
in
S, False otherwise.
|
| isalpha(...)
| S.isalpha() -> bool
|
| Return True
if
all characters
in
S are alphabetic
| and there is at least one character
in
S, False otherwise.
|
| isdigit(...)
| S.isdigit() -> bool
|
| Return True
if
all characters
in
S are digits
| and there is at least one character
in
S, False otherwise.
|
| islower(...)
| 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.
|
| isspace(...)
| S.isspace() -> bool
|
| Return True
if
all characters
in
S are whitespace
| and there is at least one character
in
S, False otherwise.
|
| istitle(...)
| S.istitle() -> bool
|
| Return True
if
S is a titlecased string and there is at least one
| character
in
S, i.e. uppercase characters may only follow uncased
| characters and lowercase characters only cased ones. Return False
| otherwise.
|
| isupper(...)
| 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.
|
|
join
(...)
| S.
join
(iterable) -> string
|
| Return a string
which
is the concatenation of the strings
in
the
| iterable. The separator between elements is S.
|
| ljust(...)
| S.ljust(width[, fillchar]) -> string
|
| Return S left-justified
in
a string of length width. Padding is
|
done
using the specified fill character (default is a space).
|
| lower(...)
| S.lower() -> string
|
| Return a copy of the string S converted to lowercase.
|
| lstrip(...)
| S.lstrip([chars]) -> string or unicode
|
| Return a copy of the string S with leading whitespace removed.
| If chars is given and not None, remove characters
in
chars instead.
| If chars is unicode, S will be converted to unicode before stripping
|
| partition(...)
| 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.
|
| replace(...)
| S.replace(old, new[, count]) -> string
|
| Return a copy of string S with all occurrences of substring
| old replaced by new. If the optional argument count is
| given, only the first count occurrences are replaced.
|
| rfind(...)
| 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.
|
| rindex(...)
| S.rindex(sub [,start [,end]]) -> int
|
| Like S.rfind() but raise ValueError when the substring is not found.
|
| rjust(...)
| S.rjust(width[, fillchar]) -> string
|
| Return S right-justified
in
a string of length width. Padding is
|
done
using the specified fill character (default is a space)
|
| rpartition(...)
| 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.
|
| rsplit(...)
| S.rsplit([sep [,maxsplit]]) -> list of strings
|
| Return a list of the words
in
the string 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 or is None, any whitespace string
| is a separator.
|
| rstrip(...)
| S.rstrip([chars]) -> string or unicode
|
| Return a copy of the string S with trailing whitespace removed.
| If chars is given and not None, remove characters
in
chars instead.
| If chars is unicode, S will be converted to unicode before stripping
|
|
split
(...)
| S.
split
([sep [,maxsplit]]) -> list of strings
|
| Return a list of the words
in
the string 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.
|
| splitlines(...)
| S.splitlines(keepends=False) -> 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
.
|
| startswith(...)
| 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.
|
| strip(...)
| S.strip([chars]) -> string or unicode
|
| 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.
| If chars is unicode, S will be converted to unicode before stripping
|
| swapcase(...)
| S.swapcase() -> string
|
| Return a copy of the string S with uppercase characters
| converted to lowercase and vice versa.
|
| title(...)
| S.title() -> string
|
| Return a titlecased version of S, i.e. words start with uppercase
| characters, all remaining cased characters have lowercase.
|
| translate(...)
| S.translate(table [,deletechars]) -> string
|
| Return a copy of the string S, where all characters occurring
|
in
the optional argument deletechars are removed, and the
| remaining characters have been mapped through the given
| translation table,
which
must be a string of length 256 or None.
| If the table argument is None, no translation is applied and
| the operation simply removes the characters
in
deletechars.
|
| upper(...)
| S.upper() -> string
|
| Return a copy of the string S converted to uppercase.
|
| zfill(...)
| S.zfill(width) -> string
|
| Pad a numeric string S with zeros on the left, to fill a field
| of the specified width. The string S is never truncated.
|
| ----------------------------------------------------------------------
| Data and other attributes defined here:
|
| __new__ = <built-
in
method __new__ of
type
object>
| T.__new__(S, ...) -> a new object with
type
S, a subtype of T
|
本文转自 曾哥最爱 51CTO博客，原文链接：http://blog.51cto.com/zengestudy/1790771，如需转载请自行联系原作者
