python3.0 Third Day file operations

File operations

Procedure for file operation

1. Open the file, get the file handle and assign a value to a variable
2. Manipulating a file with a handle
3. Close File

The existing files are as follows

Somehow, it seems the love I knew is always the most destructive kind I don't know why I went through the most devastating of the kind yesterday when I am young Yesterday when I was young and frivolous the taste of life is sweet as rain upon my tongue as rain on the tip of the tongue I teased at live asifit were a foolish game I tease life and see it as a foolish play the evening breeze is like the night breeze may tease the candle flame tease the flame of the candle the Thousand Dr Eams I dreamed I have dreamed of the splendid things I planned those I plan the brilliant blueprint I always built to last on weak andshifting sand but I always built it on the sands of the perishable I lived by Night andshunned the naked light of day I singer to escape the day naked sun and just now I saw how the time ran away it's time for me to see how the years passed yesterday when I was young yesterday when I was teenage so many lovely songs were waiting to be sung there are so many sweet longtaisheng waiting for me to sing so many wild pleasures layinchStore forI have so many wanton pleasures and so I enjoy and so much pain my eyes refused to see there's so much pain in my eyes but I'm blind I ran so fast that time andYouth at the last run out I'm running out of time and my youth is gone I never stopped to think I am all about I never stop to think about the meaning of life and every Conve Rsation that I can now recall all conversations recalled today concerned itself with me andNothingElseat all I can't remember anything else about me. The game of love I played with arrogance andPride I play the Game of love with conceit and arrogance and every flame I lit too quickly, quickly died all the flames I lit were extinguished too fast the friends I made all somehow seemed To slip away all my friends seem to have left unconsciously and only now I'm left alone to end the play, yeahI'm the only one left on the stage to end this farce Oh, yesterday when I am young oh yesterday when my youth so many, many songs were waiting to be sung there are so many sweet longtaisheng so I sing so M Any wild pleasures layinchStore forI have so many wanton pleasures and so I enjoy and so much pain my eyes refused to see there's so much pain in my eyes but I'm blind there is so many songsinchMe that won't be sungI've got too many songs I'll never be sung I feel the bitter taste of tears upon my tongue I tasted the bitter taste of the tongue of tears the time has come forMe to pay foryesterday finally came to pay the price of time for yesterday when I am young i

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Basic operations

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f =open(‘lyrics‘) #打开文件first_line =f.readline()print(‘first line:‘,first_line) #读一行print(‘我是分隔线‘.center(50,‘-‘))data =f.read()# 读取剩下的所有内容,文件大时不要用print(data) #打印文件f.close() #关闭文件

The mode of opening the file is:

• R, read-only mode (default).
• W, write-only mode. "unreadable; not exist; create; delete content;"
• A, append mode. "Readable; not exist" create; "only append content;"

"+" means you can read and write a file at the same time

• r+, can read and write files. "readable; writable; can be added"
• w+, write and read
• A +, with a

"U" means that the \ r \ n \ r \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ r or r+ mode can be converted automatically when reading

• RU
• R+u

"B" means processing binary files (e.g. FTP send upload ISO image file, Linux can be ignored, Windows process binary file should be labeled)

• Rb
• Wb
• Ab

Other syntax

    def close (self): # real signature unknown;                Restored from __doc__ "" "Close the file.  A closed file cannot is used for further I/O operations.        Close () May is called more than once without error. "" "Pass Def Fileno (self, *args, **kwargs): # Real signature Unknown" "" Return the underlying file descr Iptor (an integer).  "" "Pass Def Isatty (self, *args, **kwargs): # Real signature Unknown" "" True if the file was connected to A TTY device. "" "Pass Def Read (self, size=-1): # known case of _io.                Fileio.read "" "Note that you may not be able to read it all back. Read at the most size bytes, returned as bytes.        Only makes one system call, so less data is returned than requested.        In non-blocking mode, returns None if the data is available.        Return an empty bytes object at EOF. "" "" Return "" Def readable (self, *args, **kwargs): # Real signature Unknown "" "True If File is opEned in a read mode. "" "Pass Def ReadAll (self, *args, **kwargs): # Real signature Unknown '" "" Read all data from the F                Ile, returned as bytes.  In non-blocking mode, returns as much as are immediately available, or None if no data is available.        Return an empty bytes object at EOF. "" "Pass Def Readinto (self): # real signature unknown;        Restored from __doc__ "" "Same as Rawiobase.readinto ()." "" Pass #不要用, no one knows what it's for. Def seek (self, *args, **kwargs): # Real signature Unknown "" "Move to new file posit                Ion and return the file position.  Argument offset is a byte count. Optional argument whence defaults to Seek_set or 0 (offset from start of file, offset should be >= 0); Other values is seek_cur or 1 (move relative to current position, positive or negative), and seek_end or 2 (move relative to end of file, usually negative, although many platforms allow SEeking beyond the end of a file).        Note that not all file objects is seekable. "" "Pass Def seekable (self, *args, **kwargs): # Real signature Unknown" "" True if file supports Random-a Ccess.                "" "Pass Def Tell (self, *args, **kwargs): # Real signature Unknown '" "" Current file position.        Can raise oserror for non seekable files.  "" "Pass def truncate (self, *args, **kwargs): # Real signature unknown '" "truncate the file to at                Most size bytes and return the truncated size.        Size defaults to the current file position, as returned by Tell ().        The current file position was changed to the value of size. "" "Pass Def writable (self, *args, **kwargs): # Real signature Unknown" "" True if file is opened in a W Rite mode. "" "Pass Def write (self, *args, **kwargs): # Real signature Unknown '" "" Write bytes B to file, ret Urn NumbEr written.        Only makes one system call, so is not all of the data is written.  The number of bytes actually written is returned.        In non-blocking mode, returns None if the write would block. "" "Pass

With statement

To avoid forgetting to close a file after opening it, you can manage the context by:

123	with open(‘log‘,‘r‘) as f:        ...

This way, when the with code block finishes executing, the internal automatically shuts down and frees the file resource.

After Python 2.7, with also supports the management of multiple file contexts simultaneously, namely:

12	with open(‘log1‘) as obj1, open(‘log2‘) as obj2:    pass

python3.0 Third Day file operations