Python File Handling | File Operations in Python | Learn python programming | Edureka

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Agenda
File Handling In Python

Agenda
Introduction 01
Why need File Handling?
Getting Started 02
Concepts 03
Practical Approach 04
Types of Files
Looking at code to
understand theory
Python File Handling System

Why need File Handling?

Why Need File Handling?
Python Input
Arguments Standard Input
Files

Types of Files

Types Of Files
What you may know as a file is slightly different in Python
Text
BinaryImage Text
AudioExecutable

What is File Handling?

What Is File Handling?
File handling is an important part of any web application
Operations
Creating DeletionReading Updating
CRUD

The key function for working with files in Python is the open() function
open()
Filename Mode
Syntax open( filename, mode)
WORK
Create File
Open File
WORK
Close File

The key function for working with files in Python is the open() function
Syntax open( filename, mode)
Any name that you want
Different 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
"t" - Text - Default value. Text mode
"b" - Binary - Binary mode (e.g. images)
In addition you can specify if the file should be handled as binary or text mode

Example Code
Example f = open(“demofile.txt”)
Example f = open(“demofile.txt”, “r”)
Note: Make sure file exists or else error!

File Operations for Reading

Reading Text File In Python
file.read()
Example
> file = open(“testfile.text”, “r”)
> print file.read()
Lots of ways to read a text file in Python
All characters Some characters

file.read()
Example
> print file.read()
Example
> print file.read(5) This 5 indicates what?

file.read()
Example
> print file.readline(): Line by line output
Example
> print file.readline(3): Read third line only
Example
> print file.readlines(): Read lines separately

Looping Over A File Object
Fast and efficient!
Example
> for line in file:
> print file.readline():
Looping over the object
Reading from files

Python File Write Method

File Write Method
Writing 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
Example
> f = open("demofile.txt", "a")
> f.write(“ We love Edureka!")
Example
> f = open("demofile.txt", “w")
> f.write(“ We love Edureka!")
Note: the "w" method will
overwrite the entire file.

File Write Method
Example
> file = open(“testfile.txt”, “w”)
> file.write(“This is a test”)
> file.write(“To add more lines.”)
> file.close()
I’m writing files!

Creating a New File

Creating A New File
open() method again
➢ file = open(“testfile.txt”, “x”)
➢ file = open(“testfile.txt”, “w”)
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

Deletion Operations

Deleting A File
os.remove() function
To delete a file, you must import the OS module, and run its os.remove() function:
Example
> import os
> os.remove("demofile.txt")
Deleting a folder?
Example
> import os
> os.rmdir("myfolder")
Check if file exists
> import os
> if os.path.exists("demofile.txt"):
> os.remove("demofile.txt")
> else:
> print("The file does not exist")

Conclusion

Python File Handling | File Operations in Python | Learn python programming | Edureka

Python File Handling | File Operations in Python | Learn python programming | Edureka

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