Python Development "section 6th", "File Operations"

1. Basic file operation

• Open () Opens or creates a file

Format: Open (' file path ',' open mode ')    return value: File IO object open mode altogether n kinds:        W-mode write mode  when the write file does not exist when the file is created, if the file already exists it will empty the file        R mode  Reading mode read  file does not exist on the error, there is ready to read the file        a mode append mode append File does not exist then new, file exists then append to the end of file        x mode or schema file exists error, file does not exist then new file        B mode binary mode binary auxiliary mode cannot use         + mode enhanced mode Plus  also auxiliary mode cannot be used alone

• Close () closes the file

format: File IO object. Close () return value: None # Create a new file with the file name: test.txtf = open ('test.txt'w')  #  close this file

• Read () reading files

Format: File IO object. Read ()    return value: The character format of the entire file: File IO object. read (character length)    return value: A character of the specified length

• ReadLine () reads a row of files

format: File IO object. ReadLine ()    return value: String format for a single line of content: File IO object. readline (character length)    return value: string of one line note: Character length < current inline content Reads a string of the specified length, and the next time it reads or gets the content that is     not read in this row. Character length >= the current line content, directly read the forward

• ReadLines () reads the contents of the file into the sequence.

Format: File IO object. ReadLines ()    return value: List format: File IO object. readlines (character length)    return value: List Note: The number of rows read is determined by the length of the character, and if the character length reads n rows, there are also characters of the specified length     without reading, the next line is read directly in

• Write () writes to file

Format: File IO object. Write (string: str)    return value: The length of the write string

• Writelines () writes the sequence to the file

Format: File IO object. writelines (sequence: list)    return value: None

2. OS module file and folder operation

Functions in the OS module:

Serial Number	Function Name	Description	format
1	GETCWD ()	Get the current working directory	Format: OS.GETCWD () Return value: Path string
2	ChDir ()	Modify the current working directory	Format: Os.chdir () return value: None
3	Listdir ()	Gets the specified folder in the List of all files and folders	Format: Os.listdir (directory path) Return value: List of content names in the directory
4	mkdir ()	Create a Directory/folder	Format: Os.mkdir (directory path) return value: None
5	Makedirs ()	To create a folder recursively	Format: os.makedirs (PATH)
6	RmDir ()	Remove a directory (must be an empty directory)	Format: Os.rmdir (directory path) return value: None
7	Removedirs ()	To delete a folder recursively	Format: Os.removedirs (directory path) return value: None Note the lowest-level directory must be empty
8	Rename ()	Modify the names of files and folders	Format: os.rename (source file or folder, destination file or folder) return value: None
9	Stat ()	Get information about a file	Format: Os.stat (file path) Return value: A tuple containing file information
10	System ()	Execute system command	Format: Os.system () Return value: Integral type Use with caution! You're going to have fun with a RM-RF!
11	Getenv ()	Get System Environment variables	Format: os.getenv (Gets the environment variable name) return value: String
12	Putenv ()	Setting System Environment variables	Format: os.putenv (' environment variable name ', value) return value: None Note: The getenv is not detected properly.
13	Exit ()	Launches the current execution command to directly close the current operation	Format: Exit () return value: None

3, OS. Path module

OS. Path Module Function section:

Serial Number	Function Name	Description	format
1	Abspath ()	Convert a relative path to an absolute path	Format: Os.path.abspath (relative path) return value: Absolute path string
2	BaseName ()	Get the folder or file name in the path (As long as the last part of the path)	Format: os.path.basename (PATH) Return value: The last part of the path (possibly a file name or a folder name)
3	DirName ()	Gets the path part of the path (out of the last part)	Format: os.path.dirname (PATH) Return value: The content string in the path except the last part
4	Join ()	Synthesize 2 paths into one path	Format: Os.path.join (path 1, path 2) Return value: The path after merging
5	Split ()	Cut a path into the folder and filename section	Format: os.path.split (PATH) return value: Tuple
6	Splitext ()	Cut a file name into a two-part name and suffix	Format: Os.path.splitext (file name) return value: Tuple (name, suffix)
7	GetSize ()	Get the size of a file	Format: os.path.getsize (PATH) return value: Integer
8	Isfile ()	Detects if a path is a file	Format: os.path.isfile (PATH) Return Value: Boolean value
9	Isdir ()	Detects if a path is a folder	Format: Os.path.isdir (PATH) Return Value: Boolean value
10	Getctime ()	Gets the creation time of the file! Get Create Time	Format: Os.path.getctime (file path) Return value: Time stamp floating point number
11	Getmtime ()	Get the file modification time! Get Modify Time	Format: Os.path.getmtime (file path) Return value: Time stamp floating point number
12	Getatime ()	Get the file access time! Get active Time	Format: Os.path.getatime (file path) Return value: Time stamp floating point number
13	Exists ()	Detects if the specified path exists	Format: os.path.exists (PATH) Return Value: Boolean value
14	Isabs ()	Detects if a path is an absolute path	Format: os.path.isabs (PATH) Return Value: Boolean value
15	Islink ()	Detects if a path is a link	Format: Os.path.islink (PATH) Return Value: Boolean value
16	Samefile ()	Detects if 2 paths point to the same file	Format: Os.path.samefile (path 1, path 2) Return Value: Boolean value

Python Development "section 6th", "File Operations"