Python file-like Object: file read/write

Official website to explain the operation of the document:

open(file, mode= ' R ', Buffering=-1, Encoding=none, Errors=none, Newline=none, closefd=true, Opener=none)

Character	meaning
'r'	Open for reading (default)
'w'	Open for writing, truncating the file first
'x'	Open for exclusive creation, failing if the file already exists
'a'	Open for writing, appending to the end of the file if it exists
'b'	Binary mode
't'	Text mode (default)
'+'	Open a disk file for updating (reading and writing)
'U'	Universal newlines Mode (deprecated)

The default mode is'r'(Open for reading text, synonym of'rt'). For binary read-write access, the mode'w+b'Opens and truncates the file to 0 bytes.'r+b'Opens the file without truncation.

Https://docs.python.org/3/library/functions.html#open

Text Read and write operations: open (), close (), read (), ReadLines (),

One, normal operation, open (), read (), close ()

#!/usr/bin/python#coding=utf-8import loggingtry:f = open ('/home/seeing-zynq/documents/temp/ test/mydict.py ',  ' R ') print f.read ();p rint  ' read ' except exception as e: Logging.exception (e) print  ' ERROR ' raise finally:if f:f.close () print  ' OK ' 

run Result:

#!/usr/bin/python#-*-coding:utf-8-*-class Dict (Dict): Def __init__ (self, **kw): Super (). __init__ (**kw) de F __getattr__ (Self, key): Try:return Self[key] except keyerror:raise attributeerror ( R "' Dict ' object have no attribute '%s '"% key "Def __setattr__ (self, Key, value): self[key] = Valuereadok

Second, read () automatically close after completion ()

with open ('/home/seeing-zynq/documents/temp/test/mydict.py ',  ' r ')  as f:     print  (F.read ()) 

run Result:

#!/usr/bin/python#-*-coding:utf-8-*-class Dict (Dict): Def __init__ (self, **kw): Super (). __init__ (**kw) de F __getattr__ (Self, key): Try:return Self[key] except keyerror:raise attributeerror ( R "' Dict ' object have no attribute '%s '"% key "Def __setattr__ (self, Key, value): self[key] = value

Third, in order to avoid the read () unknown capacity of large files, for insurance purposes with readlines ().

print  '------------------------------------' print  '-----------------------------------' f =  open ('/home/seeing-zynq/documents/temp/test/mydict.py ',  ' R ') For line in f.readlines ( ):     print (Line.strip ())   # #strip会将前面首字符前的空格去掉, resulting in a line sentence without indentation f.close () print  ' Over ' 

Operation Result:

-----------------------------------------------------------------------#!/usr/bin/python#-*-coding:utf-8-*- Class Dict (Dict):d ef __init__ (Self, **kw): Super (). __init__ (**KW) def __getattr__ (self, key): Try:return Self[key] Except Keyerror:raise Attributeerror (r "' Dict ' object have no attribute '%s '"% key) def __setattr__ (self, Key, value): Self[k EY] = Valueover

Four, read binary files, tablets, videos, etc.

>>> f = open ('/users/michael/test.jpg ', ' RB ') >>> f.read () b ' \xff\xd8\xff\xe1\x00\x18exif\x00\x00 ... ' # Hexadecimal representation of bytes

V. Write ()

with open ('/home/seeing-zynq/documents/temp/io/a.txt ',  ' W ')  as f:        f.write (' haha ') with open ('/home/seeing-zynq/documents/temp/io/a.txt ',  ' r ')  as  f:      print  (F.read ()) "file.py"  37l, 758c wri 

Operation Result:

haha

Python file-like Object: file read and write