Python3 manual-Basic Data Type-string

Judgement-A bool value is usually returned.
Str. isalpha ()	Whether to include only text
Str. isdecimal ()	Whether to include only numbers (multilingual numbers)
Str. isdigit ()	Whether to include only numbers (0 ~ 9)
Str. isnumeric ()	Whether to contain only numeric characters
Str. isalnum ()	Whether it only contains text and numbers
Str. isidentifier ()	Is it a legal identifier?
Str. islower ()	Lowercase?
Str. isupper ()	Are all uppercase letters?
Str. istitle ()	Whether the first letter of each word is capitalized
Str. isprintable ()	Whether to include only printable characters
Str. isspace ()	Whether to contain only white space characters
Str. startswith (prefix [, Start [, end])	Prefix or not
Str. endswith (suffix [, Start [, end])	End with suffix?
Modifier-a modified string is usually returned.
Str. capitalize ()	Returns an uppercase string.
Str. Title ()	Returns an uppercase string of each word.
Str. expandtabs ([tabsize])	"\ T" to convert to Space
Str. Upper ()	Full conversion to uppercase
Str. Lower ()	Convert all to lowercase letters
Str. Ljust (width [, Fillchar])	Align left and fill right
Str. Must ust (width [, Fillchar])	Right alignment, left Filling
Str. Center (width [, Fillchar])	Center, filled on both sides
Str. lstrip ([chars])	Remove left white space or custom characters
Str. rstrip ([chars])	Remove right white space or custom characters
Str. Strip ([chars])	Remove white spaces or custom characters on both sides
Str. swapcase ()	Case sensitivity
Str. zfill (width)	Fill the left side with 0 to the specified width, which is generally used to modify numbers
Search & replace
Str. Count (sub [, Start [, end])	Calculate the number of sub occurrences between [start, end)
Str. Find (sub [, start [, end])
Str. Index (sub [, start [, end])
Str. rfind (sub [, start [, end])
Str. rindex (sub [, start [, end])
Str. Replace (old, new [, Count])
Splitting & Combination
Str. Join (iterable)
Str. Partition (SEP)
Str. rpartition (SEP)
Str. Split ([Sep [, maxsplit])
Str. rsplit ([Sep [, maxsplit])
Str. splitlines ([keepends])
Conversion
Hex (X)
INT ([number | string [, base])
Len (s)
List ([iterable])
Oct (X)
Ord (c)
Repr (object)
Reversed (SEQ)
STR ([object [, encoding [, errors])

Upper top priority Str. isalpha ()
-Whether to include only text

Code	Result
Print ("China ABC". isalpha ())	True
Print ("". isalpha ())	False
Print ("123". isalpha ())	False
Print ("". isalpha ())	False

Maximum top priority Str. isdecimal ()
-Whether to include only decimal numbers, including multilingual numbers

Code	Result
Prints ("1234567890". isdecimal ())	True
Print ("\ u0660". isdecimal ())	True
Print ("ABC". isdecimal ())	False
Print ("". isdecimal ())	False

For numbers in other languages see http://www.fileformat.info/info/unicode/category/Nd/list.htm

Upper top priority Str. isdigit ()
-Whether to include only numbers (0 ~ 9)

Code	Result
Print ("1234567890". isdigit ())	True
Print ("\ u0660". isdigit ())	True
Print ("ABC". isdigit ())	False
Print ("". isdigit ())	False

Maximum top priority Str. isnumeric ()
-Whether to include only numeric characters

Code	Result
Print ("1234567890". isnumeric ())	True
Print ("\ u2155". isnumeric ())	True
Print ("ABC". isnumeric ())	False
Print ("". isnumeric ())	False

For numeric characters, see http://www.fileformat.info/info/unicode/category/No/list.htm

Maximum top priority Str. isalnum ()
-Whether to include only text and numbers

Code	Result
Print ("abc123456 \ u2155". isalnum ())	True
Print ("". isalnum ())	False
Print ("\ t". isalnum ())	False
Print ("". isalnum ())	False

Maximum top priority Str. isidentifier ()
-Is it a legal identifier?

Code	Result
Print ("if". isidentifier ())	True
Print ("China". isidentifier ())	True
Print ("123". isidentifier ())	False
Print ("". isidentifier ())	False

Comment top comment Str. islower ()
-Whether it is in lower case

Code	Result
Print ("ABC". islower ())	True
Print ("ABC". islower ())	False
Print ("China". islower ())	False
Print ("". islower ())	False

Upper top priority Str. isupper ()
-Are all uppercase letters?

Code	Result
Print ("Hello world". istitle ())	True
Print ("Hello world". istitle ())	False
Print ("Hello world". istitle ())	False
Print ("". istitle ())	False

Upper top priority Str. istitle ()
-Whether the first letter of each word is capitalized

Code	Result
Print ("Hello world". istitle ())	True
Print ("Hello world". istitle ())	False
Print ("Hello world". istitle ())	False
Print ("". istitle ())	False

Wrote top response Str. isprintable ()
-Whether to include only printable characters

Code	Result
Print ("a B". isprintable ())	True
Print ("". isprintable ())	True
Print ("ABC \ t". isprintable ())	False
Print ("ABC \ n". isprintable ())	False

Maximum top priority Str. isspace ()
-Whether to include only white space characters

Code	Result
Print ("". isspace ())	True
Print ("\ t \ n". isspace ())	True
Print ("a B". isspace ())	False
Print ("". isspace ())	False

Upper top priority Str. startswith (prefix [,
Start [, end])-whether to start with prefix

Code	Result
Print ("Chinese". startswith ("medium "))	True
Print ("Chinese". startswith ("China", "I ")))	True

Wrote top response Str. endswith (suffix [,
Start [, end])-whether to end with suffix

Code	Result
Print ("Chinese". endswith ("person "))	True
Print ("Chinese". endswith ("Chinese", "I ")))	True

Upper top priority Str. capitalize ()
-Returns an uppercase string.

Code	Print ("the first sentence. The second sentence.". capitalize ())
Result	The first sentence. The second sentence.

Top priority Str. Title ()
-Returns an uppercase string of each letter.

Code	Print ("this is a title". Title ())
Result	This is a title

Using Top response Str. expandtabs ([tabsize])
-"\ T" to convert to Space

Code	"\ T". expandtabs (8)
Result	''

Upper top priority Str. Upper ()
-Full conversion to uppercase

Code	Print ("ABC". Upper ())
Result	ABC

Comment top comment Str. Lower ()
-Convert all data to lowercase letters.

Code	Print ("ABC". Upper ())
Result	ABC

Upper top priority Str. Ljust (width [,
Fillchar])-align left and fill right

Code	Print ("I". Ljust (4, ""))
Result	We

Upper top priority Str. Must ust (width [,
Fillchar])-Right alignment, left Filling

Code	Print ("I". Allowed ust (4, "= "))
Result	=== Me

Upper top priority Str. Center (width [,
Fillchar])-center, filled on both sides

Code	Print ("I Am a split line". Center (30, "= "))
Result	================ I am a split line ======================

Upper top priority Str. lstrip ([chars])
-Remove left white space or custom characters

Code	'Spacious '. lstrip ()
Result	'Spacious'
Code	'Www .example.com '. lstrip ('cmowz .')
Result	'Example. com'

Upper top priority Str. rstrip ([chars])
-Remove right white spaces or custom characters

Code	'Spacious '. rstrip ()
Result	'Spacious'
Code	'Mississippi '. rstrip ('ipz ')
Result	'Mississ'

Upper top priority Str. Strip ([chars])
-Remove blank spaces or custom characters on both sides

Code	'Spacious '. Strip ()
Result	'Spacious'
Code	'Www .example.com '. Strip ('cmowz .')
Result	'Example'

Using Top response Str. swapcase ()
-Case-insensitive Conversion

Code	Print ("ABC". swapcase ())
Result	ABC

Upper top response Str. zfill (width)
-Fill the left side with 0 to the specified width, which is generally used to modify numbers.

Code	Print ("15". zfill (8 ))
Result	00000015
Code	Print ("-15". zfill (8 ))
Result	-0000015

Running Top response Str. Count (sub [,
Start [, end])-calculates the number of sub occurrences between [start, end ).

Code	Print ("abababab". Count ("Abab ")
Result	2

Note: non-overlapping count, so the result is 2 instead of 3