Python notes (data type)

Numeric type: integer (int), long Integer (length), floating-point number (float), plural (complex), no need to specify numeric types when defining variables, such as: A=1, a=12.5

Operators: In addition to subtraction and powers * *, Division/, divide//, remainder%, or |, Xor ^, and, left-shift operation <<, right shift operation >>.

String: String can be circled with single and double quotes, such as: A= ' 123456 is a number '

Escape character: \ n line break, \ t tab, \ r carriage return, \ \ = \,\ ' represents single quotes instead of string ends, \ ' represents double quotes.
For example:
A= ' I'm just a single quote instead of an end! I can still change the line! '
Print (a)
Run Result:
c:\>a.py
' I'm just a single quote, not an end!
I can also change lines!
If you need to output \ n, the code is \\n.

Action character (omitted a= ' ABCDE ') in the instance:
Capitalize ()--Capitalize the first letter: print (A.capitalize ()) to run the result to ABCDE
count ()--Get the number of a substring:p rint (A.count (' B ')) The result of the run is 1,b only once
find ()--Gets the starting position of a string: print (A.find (' B ')) results in 1, that is, the second digit.
Isalnum ()--detects whether numbers and uppercase and lowercase letters are included: print (A.isalnum ()) returns True
Isalpha ()--detects whether to include uppercase and lowercase
isdigit ()--to detect if a number is included
Islower ()--detects whether all lowercase letters
isspace ()--detects that all characters in a string are white space characters
Istitle ()--detects whether the initials uppercase
Isupper ()--detects whether all uppercase
joins ()--Connection string: print (A.join (' OK)) returns to Oabcdek
Lower ()--converts a string to lowercase
split ()--Split string: Print (A.split (' C ')) returns [' AB ', '] De '
Swapcase ()--converts lowercase to uppercase and converts the original capitalization to lowercase
title ()--capitalize the first letter of the word a= ' Hello word ' and return to Hello Word
Upper ()-- Converts a string to uppercase
Len (str)--Detect string length: Len (a) returns to 5

Index and fragmentation of strings:
accesses the character at the specified position in the string, 0 as the leading character, and-1 is the lowest character.
>>> a= ' abcde '
>>> a[1]
' B '
----------------------------------------------
> >> a[-1]
' e '
----------------------------------------------
[] can use the structure of [n:m], meaning to start with the nth character, and take the M character , but does not contain the M character
>>> a= ' ABCDEFG '
>>> a[0:5]
' ABCDE '

Original string:
starting with uppercase or lowercase r, where \ does not represent escape
>>> import os
>>> path=r ' C: '
>>> os.listdir ( Path
[' $360section ', ' $Recycle. Bin ', ' 360SANDBOX ', ' a.py ', ' AMD ', ' Autoexec.bat ', ' Bo
ot ', ' bootmgr ', ' bootsect . BAK ', ' cflog ', ' cimtemp ', ' Config.sys ', ' Documents and
 settings ', ' ghost.bat ', ' Ghost.exe ', ' grldr ', ' Grldr.mbr ', ' lbgsn ', ' lib ', ' Neo
Shineoffice 5 ', ' Okldr ', ' okldr.mbr ', ' OneKey.exe ', ' Oracle ', ' PerfLogs ', ' Progr
Am Files ', ' programdata ', ' Python34 ', ' System Volume information ', ' TeamViewer ',
  ' Temp ', ' Uninstall. ', ' Users ', ' Vb ', ' Vb7 ', ' vc# ', ' Windows ', ' Ylmf.ima ']