Python File Handling

If you are interested to learn about the Python Iterators

Python too supports file handling and allows users to handle files i.e., to read and write files, along with many other file handling options, to operate on files. The concept of file handling has stretched over various other languages, but the implementation is either complicated or lengthy, but like other concepts of Python, this concept here is also easy and short. Python treats file differently as text or binary and this is important. Each line of code includes a sequence of characters and they form text file. Each line of a file is terminated with a special character, called the EOL or End of Line characters like comma {,} or newline character. It ends the current line and tells the interpreter a new one has begun. Let’s start with Reading and Writing files. 

How are files handled in Python?

Python has a built-in open() function to open a file. This function returns a file object, also called a handle, as it is used to read or modify the file accordingly. We can specify the mode while opening a file. In mode, we specify whether we want to read r , write w or append a to the file.

Why does Python require file handling?

Python file handling (a.k.a File I/O) is one of the essential topics for programmers and automation testers. It is required to work with files for either writing to a file or read data from it. Also, if you are not already aware, I/O operations are the costliest operations where a program can stumble.

Python File Open

File handling is an important part of any web application. Python has several functions for creating, reading, updating, and deleting files.

File Handling

The key function for working with files in Python is the open() function. The open() function takes two parameters; filename, and mode. There are four different methods (modes) for opening a file:

"r" – Read – Default value. Opens a file for reading, error if the file does not exist

"a" – Append – Opens a file for appending, creates the file if it does not exist

"w" – Write – Opens a file for writing, creates the file if it does not exist

"x" – Create – Creates the specified file, returns an error if the file exists

In addition you can specify if the file should be handled as binary or text mode

"t" – Text – Default value. Text mode

"b" – Binary – Binary mode (e.g. images)


To open a file for reading it is enough to specify the name of the file:

f = open("demofile.txt").

The code above is the same as:

f = open("demofile.txt", "rt") 

Because "r" for read, and "t" for text are the default values, you do not need to specify them.

Note: Make sure the file exists, or else you will get an error.

Open a File on the Server

Assume we have the following file, located in the same folder as Python:

demofile.txtHello! Welcome to demofile.txt
This file is for testing purposes.
Good Luck!

To open the file, use the built-in open() function. The open() function returns a file object, which has a read() method for reading the content of the file:


f = open("demofile.txt", "r")<br>print(

If the file is located in a different location, you will have to specify the file path, like this:


Open a file on a different location

f = open("D:\\myfiles\welcome.txt", "r")<br>print(

Read Only Parts of the File

By default the read() method returns the whole text, but you can also specify how many characters you want to return:


Return the 5 first characters of the file:

f = open("demofile.txt", "r")<br>print(<strong>5</strong>))

Read Lines

You can return one line by using the readline() method:


Read one line of the file:f = open("demofile.txt", "r")<br>print(f.readline())

By calling readline() two times, you can read the two first lines:


Read two lines of the file:

f = open("demofile.txt", "r")<br>print(f.readline())<br>print(f.readline())

By looping through the lines of the file, you can read the whole file, line by line:


Loop through the file line by line:

f = open("demofile.txt", "r")<br>for x in f:<br>  print(x)

Close Files

It is a good practice to always close the file when you are done with it.


Close the file when you are finish with it

:f = open("demofile.txt", "r")<br>print(f.readline())<br>f.close()

Python File Write

Write to an Existing File

To write to an existing file, you must add a parameter to the open() function:

"a" – Append – will append to the end of the file

"w" – Write – will overwrite any existing content


Open the file “demofile2.txt” and append content to the file:

f = open("demofile2.txt", "a")<br>f.write("Now the file has more content!")<br>f.close()

#open and read the file after the appending:

<br>f = open("demofile2.txt", "r")<br>print(


Open the file “demofile3.txt” and overwrite the content:

f = open("demofile3.txt", "w")<br>f.write("Woops! I have deleted the content!")<br>f.close()

#open and read the file after the appending:

<br>f = open("demofile3.txt", "r")<br>print(

Note: the “w” method will overwrite the entire file.

Create a New File

To create a new file in Python, use the open() method, with one of the following parameters:

"x" – Create – will create a file, returns an error if the file exist

"a" – Append – will create a file if the specified file does not exist

"w" – Write – will create a file if the specified file does not exist


Create a file called “myfile.txt”:

f = open("myfile.txt", "x")

Result: a new empty file is created!


Create a new file if it does not exist:

f = open("myfile.txt", "w")

Python Delete File

Delete a File

To delete a file, you must import the OS module, and run its os.remove() function:


Remove the file “demofile.txt”:

import os<br>os.remove("demofile.txt")

Check if File exist:

To avoid getting an error, you might want to check if the file exists before you try to delete it:


Check if file exists, then delete it:

import os<br>if os.path.exists("demofile.txt"):
<br>  os.remove("demofile.txt")<br>else:<br>  print("The file does not exist")

Delete Folder

To delete an entire folder, use the os.rmdir() method:


Remove the folder

 "myfolder":import os<br>os.rmdir("myfolder")

Note: You can only remove empty folders.

Python File Handling
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