Python File handling is an important part of any web application. It is nothing but, the operating system uses the filehandle internally when accessing the file. It is a special area of main memory that is reserved for file handling, and the size of the area determines how many files can be open at once.
Contents
- 1 Python File Handling
- 1.1 Methods for Opening File in Python
- 1.2 Reading & Writing Files in Python
- 1.3 Read( ) method
- 1.4 Write( ) Method
- 1.5 Read Lines( )
- 1.6 Renaming & Deleting files in Python
- 1.7 rename( ) method
- 1.8 remove( ) method
- 1.9 Directories in Python
- 1.10 mkdir( ) method
- 1.11 chdir( ) method
- 1.12 getcwd( ) method
- 1.13 rmdir( ) method
- 1.14 Close files
Python File Handling
Python has several functions for creating, reading, updating and deleting files.
Methods for Opening File in Python
There are 4 methods for opening files. open( ) function has two parameters i.e filename and mode.
| Modes | Function | Description |
|---|---|---|
| “r” | Read | Opens a file for reading, and shows an error if the file doesn’t exist |
| “a” | Append | Opens a file for appending, creates if a file doesn’t exist |
| “w” | Write | Opens a file for writing, creates if the file doesn’t exist |
| “x” | Create | Creates a specified file and returns an error if the files exist |
| “t” | text | It gives default values, in text mode |
| “b” | Binary | binary mode (ex: images) |
Syntax
To open a file for reading it is:
f = open(“demofile.txt”)
The above syntax is same as : f = open(“demofile.txt”, “rt”)
Here, “r” & “t” are default values, you do not need to specify them.
Reading & Writing Files in Python
The file object provides a set of access methods for accessing the files easier.
Read( ) method
It reads a string from an open file. Remember that Python strings have binary data, apart from text data.
Syntax: fileObject.read([count]);
Example
# Open a file
fo = open("foo.txt", "r+")
str = fo.read(10);
print "FreshersnowString is : ",str#
Close opened filefo.close()
Output: Read String is: Freshersnow is
Write( ) Method
It writes any string to open files. Remember that Python strings have binary data, but not only text.
Syntax: fileObject.write(string);
Example
# Open a filefo = open("foo.txt", "wb")
fo.write( "Freshersnow is awesome.\nHey Freshersnow!!\n");
#Close opend filefo.close()
Output
Freshersnow is awesome.
Hey Freshersnow
Read Lines( )
We can read the lines by using the readline( ) method.
Example
f = open("demofile.txt", "r")
print(f.readline())
Output: Hello! Welcome to demofile.txt
Renaming & Deleting files in Python
By using python file handling commands or methods we can also delete and rename the files.
rename( ) method
It will be taking two arguments. i.e current file name & new file name.
Syntax: os.rename(current_file_name, new_file_name)
Example
import osos.rename( "test1.txt", "test2.txt" )
remove( ) method
we can use the remove( ) method to delete files.
Syntax: os.remove(file_name)
Example
import
osos.remove("text2.txt")
Directories in Python
All the python file handling is stored at different directories. They are as follows:
mkdir( ) method
It helps you to create files in the new directory.
Syntax: ab.mkdir(“newdir”)
Example
import os
ab.mkdir("test")
chdir( ) method
You can use this method to change the directory.
Syntax: ab.chdir(“newdir”)
Example
import os
os.chdir("/home/newdir")
getcwd( ) method
It displays the current working directory.
Syntax: os.getcwd()
Example
import os os.getcwd()
rmdir( ) method
It deletes the directory which is passed through an argument in methods. Before removing the directory all the content should be removed.
Syntax: os.rmdir(‘dirname’)
Example
import osos.rmdir( "/tmp/test" )
Close files
After finishing the task try to close the files.
Example
f = open("demofile.txt", "r")
print(f.readline( ))
f.close( )
Output: Hello! Welcome to demofile.txt