Create read and write to a file in python

 One way to store data permanently is to store it in files.

Edit a file

To edit a file in python we use the function open .

This function takes as a first parameter the path of the file (relative or absolute) and as a second parameter the type of opening

Relative path / absolute path

A relative path in computing is a path that takes into account the read location.

An absolute path is a full path that can be read regardless of the read location.

The open function

Here is the syntax to read a file

>>>  file  =  open ( "data.txt" ,  "r" ) 
>>>  print  file 
< open  file  'data.txt' ,  mode  'r'  at  0x7ff6cf3fe4b0 >

The second parameter Note that is informed by r this parameter indicates a file open in reading .

Types of opening

There are several opening modes:

r , for read opening (READ).
w , for opening for writing (WRITE), each time the file is opened, the content of the file is overwritten. If the file does not exist python creates it.
a , for opening in append mode at the end of the file (APPEND). If the file does not exist python creates it.
b , for opening in binary mode.
t , for opening in text mode.
x , create a new file and open it for writing

Closing a file

Like any open element, it must be closed once the instructions have been completed. For that we use the method close() .

>>>  file . close ()

Read the contents of a file

To display the entire contents of a file, you can use the read on-file-object method .

# coding: utf-8

file  =  open ( "data.txt" ,  "r" ) 
print  file . read () 
file . close ()

Write to file

Here is the syntax for writing to a file:

file  =  open ( "data.txt" ,  "a" ) 
file . write ( "Hello world" ) 
file . close ()

Note that for the opening world a , if you want to write on the line, you can use the line break \n :

file  =  open ( "data.txt" ,  "a" ) 
file . write ( " \ n Hello world" ) 
file . close ()

The keyword with

There is another shorter syntax that allows you to overcome the problem of closing the file: the keyword with .

Here is the syntax:

with  open ( "data.txt" ,  "r" )  as  file : 
	print  file . read ()