Python note files

Python note files
1. Open and create a file # file () is used for file (name, mode [, buffering]) in file management. The name is the file name, and the name contains-open; does not exist. The creation mode is the open mode, r, r +, w, w +, a, a +, B, U, etc.
2. Read files

# Open () read file data = open ('file _ name') # open a file print (data. redline (), end = '') # read data from a data row using readline. seek (0) # Return to the start position of the file for line in dataprint (line, end = '') data. close () # close a file

File Reading method #1) read by row

f = open(“file.txt”)while True:line = f.readline()if line:print lineelse:break;f.close()

#2) multi-row reading

F = open('file.txt ') lines = f. readlines () # readlines () stores all f content for line in linesprint line

#3) One-time read ()

f = open(‘file.txt’)content = f.read()print contentf.close()

3. File writing

# Write (), writelines () write File f = file('file.txt ', 'W +') # w + read/write mode to open, delete the original, then write the new content line = ["hello \ n", "world \ n"] f. writelines (li) f. close () # append new content f = file('hello.txt ', 'a +') content = "goodbye" f. write (content) f. close ()

4. file Deletion # The OS module and OS. path module must be used. # The open () and file () Functions of the OS module are different from those of Python.

import osfile(‘hello.txt’, ‘w’)if os.path.exists(‘hello.txt’)os.remove(‘hello.txt’)

5. File Replication

# Use read () and write () to copy src = file(‑hello.txt "," r ") dst = file(‑hello2.txt", "w") dst. write (src. read () src. close () dst. close () # shutil module copyfile () function # copyfile (src, dst)folder file copy shutil.copyfile(#hello.txt ", #hello2.txt") # move (src, example "," .. /")#shshshutil.move(“hello2.txt ", “hello3.txt") # Move + rename

6. Rename the file

# Modify the rename () function of the file name OS module import osos.rename(“hello.txt ", “hi.txt") # modify the extension name import osfiles = OS. listdir (".) for filename in files: pos = filename. find (". ") if filename [pos + 1:] =" html ": newname = filename [: pos + 1] +" jsp "OS. rename (filename, newname)

7. Search for file content

# File search import ref1 = file(export hello.txt "," r ") count = 0for s in f1.readlines (): li = re. findall ("hello", s) # findall () queries the variable s and stores the search result in li. if len (li)> 0: count = count + li. count ("hello") print count, "hello" f1.close () # Replace file f1 = file(#hello.txt "," r ") f2 = file(#hello2.txt", "w ") for s in f1.readlines (): f2.write (s. replace ("hello", "hi") f1.close () f2.close ()

8. file comparison # The difflib module is used for sequence and file comparison.
9. Access to the configuration file # parsing the configuration file in the ConfigParser module of the Python standard library
10. Files and streams

# The sys module provides three basic stream objects: stdin, stdout, and stderr. import sys # stdin indicates the standard input sys of the stream. stdin = open(export hello.txt "," r ") # Read the file for line in sys. stdin. readlines () print line # stdout redirection output, save the output result to the file sys. stdout = open (r ". /hello.txt "," a ") print" goodbye "sys. stdout. close ()