Python: File operations

Python files can be divided into text files and binary files in the form of a file organization

Each byte of a text file is placed in an ASCII code that represents a character. The binary file stores the in-memory data as it is stored in memory as if it were on disk.

Open and Close files: open (), close ()

Format: File object =open (file specifier [, open mode] [, buffer])

f = open ("c:\\a.txt","R")# Opens the file in the form of a read  # Note that the file directory must be double \ \ \

Open mode: R W a RB WB AB r+ w+ A + rb+ wb+ ab+

R mode can only output data from memory and cannot add data like in memory

W can only write data from memory to the file cannot enter data from file to memory

A add note the current position is the end of the document

r+ w+ A + can be written and read

File properties:

f = open ("file.txt","wb")# get file name F.name         #  file.txt# Get the File open way f.mode         #  "WB"  # Get Info: File closed f.closed       #  False# close File F.close         

Read and write operation

Read ()

The
• variable = file object. read () variable = file object. read ([count
• re reads a string from an open file. It is important to note that the Python string can be binary data, not just text.

  " kk.txt contents: abcdefghijklmn   " #   Open file  fo = open ( " kk.txt   ", "  r+   "  = Fo.read (10 print  ( "  The string read is:    "  #   Close Open file  fo.close ()  #   output  The string read is: Abcdefghij 

ReadLine ()

• Reads all characters from the current position to the end of the line, including the line terminator
• Variable = file object. ReadLine () returns an empty string "" when at the end of the file

ReadLines ()

Returns a value from the current position until all rows in the end of the file form a list

Write operations

Write ()

• Writes a string at the current position and returns the number of characters
• The file object. Write (String) write () does not wrap after execution, and if a newline is required, it can be added \ n

f = open ("kk.txt""wb""Ya") Kumata!\nyou know,heyo"#  Close Open file f.close ()

# the Linux environment

Ya this is kumata!
You know,heyo

Writelines ()

• Writes all the strings in the list to the current position, sequentially
• File object. writelines (element list of strings)

Location of binary file operation files

File object. Tell (): Returns the current position

File object. Seek (offset [, reference point]), seek example see Csdn:seek ()

struct MODULE

Pack () packages the entire model and floating-point type into a binary string.

Unpack () binary packaged into integral type floating point type

Pickle module: Salting the object into binary file storage

Dump () pickle.dump (data, File object)

 import   picklelist  = ["  12   ",  " 34  " ,  " ok  " ,  "  good  "  ]f  = open ( " d: KK.PKL   ", "   WB   ") #   Binary write  pickle.dump (list,f) f.close ()  

OS Module

#file Rename rename ()Os.rename ("Current file name "," New file name ")#file Delete remove ()Os.remove ("file name")#Create a directory in the current directoryOs.mkdir ("new directory Name ")#change the current directoryOs.chdir ("directory ")#Get current directoryOS.GETCWD ()#Delete Empty directoryOs.rmdir ("directories to be deleted")

Python: File operations