Python full stack path-Series file operations

Python allows you to view and create files, add, modify, and delete files, and the functions used are open in Python3.5.x, python 2.7.x supports both file and open, but file functions are removed from the 3.5.x series. Python file opening mode {... Python can view and create files, and can add, modify, and delete file content. the function used in Python3.5.x is open, Supported at the same time in Python2.7.x fileAnd openBut removed from the 3.5.x series. fileFunction.

Python file opening method

File Handle = open ('file path', 'open mode ')

Ps:The file handle is equivalent to the variable name. the file path can be either absolute or relative.

Python file opening mode

Basic mode

Mode	Description	Notes
R	Read-only mode	File must exist
W	Write-only mode	If the file does not exist, create the file. if the file exists, clear the file content.
X	Write-only mode	The file cannot be read. if the file does not exist, it is created. if the file exists, an error is returned.
A	Append mode	The file does not exist. if the file exists, add content to the end of the file.

Tape+.

Mode	Description
R +	Read/Write
W +	Write and read
X +	Write and read
A +	Write and read

Tapeb.

Mode	Description
Rb	Binary read mode
Wb	Binary write mode
Xb	Binary write-only mode
AB	Binary append mode

Tip:When opened in the B mode, the read content is of the byte type, and the byte type also needs to be provided during writing.

Tape+Tapeb.

Mode	Description
Rb +	Binary read/write mode
Wb +	Binary read/write mode
Xb +	Binary write-only mode
AB +	Binary read/write mode

Python file reading method

Mode	Description
Read ([size])	Read all the content of the file. if the size is set, read the size byte for a long time.
Readline ([size])	Read data from one row
Readlines ()	Each row is read as an element in the list.

The file name for the test ishello.tx", The file content is:

Hello Word!123abc456abc789abc

Read

Code:

# Open the file hello.txt f = open ("hello.txt", "r") in the read-only format # assign the value to the variable cc = f to read the file content. read () # close the file f. close () # print (c) the output value of c)

Output result:

C:\Python35\python.exe F:/Python_code/sublime/Day06/file.pyHello Word!123abc456abc789abc

Readline

Code:

# Open the file hello.txt f = open ("hello.txt", "r") in a read-only mode # read the first line c1 = f. readline () # read the second row c2 = f. readline () # read the third row c3 = f. readline () # close the file f. close () # print (c1) of the first row of output read file # print (c2) of the second row of output read file # print (c3) of output read file of the third row)

Output result:

C:\Python35\python.exe F:/Python_code/sublime/Day06/file.pyHello Word!123abc

Readlines

# Open the file hello.txt f = open ("hello.txt", "r") in the read-only format # assign all the file content to cc = f. readlines () # view the data type print (type (c) # close the file f. close () # traverse the output file content for n in c: print (n)

Result

C: \ Python35 \ python.exe F:/Python_code/sublime/Day06/file. py # output data type
 
  
Hello Word! 123abc456abc789abc
 

Python file writing method

Method	Description
Write (str)	Write a string to a file
Writelines (sequence or strings)	Write multiple rows to a file. the parameter can be an iteratable object, list, and tuples.

Write

Code:

# Open the write.txt file in a read-only mode. If no file is created, the file = open ("write.txt", "w") is overwritten. # write the test writefile string into the file content. write ("test write") # close the file. close ()

write.txtFile content:

test write

Writelines

Code:

# Open an existing wr_lines.txt f = open ("wr_lines.txt", "w", encoding = "UTF-8") in a read-only mode # write a list f. writelines (["11", "22", "33"]) # close the file f. close ()

wr_lines.txtFile content:

112233

Python file operations

Close (self ):

Close opened files

f.close()

Fileno (self ):

File descriptor

 f = open("hello.txt","r")ret = f.fileno()f.close()print(ret)

Execution result:

3

Flush (self ):

Refresh the buffer content to the hard disk

f.flush()

Isatty (self ):

Checks whether the file is a tty device. if the file is a tty device, the system returnsTrueOtherwise, returnFalse

f = open("hello.txt","r")ret = f.isatty()f.close()print(ret)

Returned results:

C:\Python35\python.exe F:/Python_code/sublime/Day06/file.pyFalse

Readable (self ):

Whether it is readable. if it is readableTrueOtherwise, returnFalse

f = open("hello.txt","r")ret = f.readable()f.close()print(ret)

Returned results:

C:\Python35\python.exe F:/Python_code/sublime/Day06/file.pyTrue

Readline (self, limit =-1 ):

Read only one row of data at a time

f = open("hello.txt","r")print(f.readline())print(f.readline())f.close()

Returned results:

C:\Python35\python.exe F:/Python_code/sublime/Day06/file.pyHello Word!123

Readlines (self, hint =-1 ):

Treat each row as an element in the list.

f = open("hello.txt","r")print(f.readlines())f.close()

Returned results:

C:\Python35\python.exe F:/Python_code/sublime/Day06/file.py['Hello Word!\n', '123\n', 'abc\n', '456\n', 'abc\n', '789\n', 'abc']

• Tell (self ):

Get pointer position

f = open("hello.txt","r")print(f.tell())f.close()

Returned results:

C:\Python35\python.exe F:/Python_code/sublime/Day06/file.py0

Seek (self, offset, whence = io. SEEK_SET ):

Specify the pointer position in the file

f = open("hello.txt","r")print(f.tell())f.seek(3)print(f.tell())f.close()

Execution result

C:\Python35\python.exe F:/Python_code/sublime/Day06/file.py03

Seekable (self ):

Whether the pointer is operable

f = open("hello.txt","r")print(f.seekable())f.close()

Execution result

C:\Python35\python.exe F:/Python_code/sublime/Day06/file.pyTrue

Writable (self ):

Writable or not

f = open("hello.txt","r")print(f.writable())f.close()

Execution result

C:\Python35\python.exe F:/Python_code/sublime/Day06/file.pyFalse

Writelines (self, lines ):

The string sequence of the written files, which can be produced by any iterative object string, usuallyString list.

f = open("wr_lines.txt","w")f.writelines(["11","22","33"])f.close()

Execution result

112233

Read (self, n = None ):

Reads specified bytes of data. all data is read by default without parameters.

f = open("wr_lines.txt","r")print(f.read(3))f.seek(0)print(f.read())f.close()

Execution result

C:\Python35\python.exe F:/Python_code/sublime/Day06/file.py112112233

Write (self, s ):

Write content to the file

f = open("wr_lines.txt","w")f.write("abcabcabc")f.close()

File content

abcabcabc

Open multiple files at the same time

To avoid forgetting to close a file after it is opened, you can manage the context, that is:

With open ('log', 'r') as f: code block

In this way, when the with code block is executed, the file resources are automatically closed and released internally.

In Python 2.7 and later versions, with also supports managing the context of multiple files at the same time, namely:

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

For more articles about file operations in the full-stack Python series, refer to the PHP Chinese website!