Python learning _06_ file, IO

File Object

File manipulation in Python is similar to the C language, including some ways of buffering and offsetting.

The file object can be created by using the open (), file () two built-in methods, and the two methods are not different, similar to the fopen () in C language:

File_object = open (file_name, access_mode= ' R ', Buffering=-1)

Where Access_mode means open mode, R for Read only, W for write only, r+,w+ for read and write, a for append etc, buffering for buffering, negative for default buffering, 0 for unbuffered, 1 for row buffer, and greater than 1 for buffer size, In general, you can use the default buffer.

In Perl it is often used in the way of pipes, through open in, "GUNZIP-CD $gzfile |" or Die $!; Easy way to read from a compressed file, you can also implement pipeline operations in Python via Os.popen (), noting that the last layer of piping's | needs to be omitted because Popen () is read from the pipeline by default.

File input:

1. The read () method, specifies that a certain number of bytes are read into the string, and if no byte is specified or negative, all content is read;

2. ReadLine () method, reads a line of content, if the specified parameter size is less than one line length, returns only size bytes into the string;

3. The ReadLines () method reads all rows and returns a list of strings, the optional parameter represents the maximum number of bytes returned, but the buffer size still needs to be pooled;

Using iterators, and with the For Loop and ReadLine () methods, is the better way to enter:

For line in File_object.readline ():
? ? Print line?

File output:

1. Write () method, like file writing string

2. Writelines () method, writes a list of strings to a file, or an iterative object that returns a string

File offset:

1. The tell () method can return the current position in the file

2. Seek (offset, whence=0) method, move the pointer in the file, whence=0 means to move offset offsets from the beginning of the file, 1 means to move offset offsets from the current position, and 2 to move offset offsets from the end of a file

Built-in methods:

File.close (): Closes the file handle and writes the contents of the buffer to the file

File.fileno (): Returns the file descriptor;

File.flush (): Flush file buffers Now

Built-in properties:

File.name: filename, file.mode: File open mode, file.encoding: File Encoding method, file.closed: File is closed, etc.

Standard input and output error stream:

The SYS module can access the standard input and output error stream through Sys.stdin,sys.stdout,sys.syderr, and the built-in method Raw_input () typically receives input from Sys.stdin

The SYS module can also access the environment parameters through the SYS.ARGV property, Argv[0] as the script itself

File system

The OS module contains the main interfaces of the operating system functionality, including the related operations of the file:

OS.GETCWD (): Returns the current working directory, Os.listdir (): Lists the relevant files (including subdirectories) in the specified directory, chdir (): Change the current directory, Symlink (): Create Symbolic Link, remove (): Delete file, rename () : Renaming files

Path-related operations in the Os.path module:

Os.path.basename: Return file name, dirname (): Returns the directory name, Split (): Returns (DirName (), basename ()) tuple, Get*time (): Returns various events, GetSize () returns the file size, Exists (): Specifies whether the path exists, Isdir (): Whether the specified path exists and is a directory, Isfile (): Specifies whether the directory exists and is a file, and so on

Other related modules

BZ2, CSV, Gzip/zlib, Tarfile, ZipFile, etc.

Python learning _06_ file, IO