File Handling

Introduction to Files

A file is a collection of data stored on a storage device. Files allow programs to store data permanently, unlike variables which store data temporarily in memory.

Types of Files

• Text Files: Store readable data (e.g., .txt, .csv)
• Binary Files: Store non-readable data (e.g., images, videos)

Why File Handling is Important

• Store large data permanently
• Retrieve data when needed
• Share data between programs
• Useful in real-world applications like logs, reports, and databases

---

• Opening and Closing Files

open() Function

Used to open a file.

file = open("example.txt", "r")

File Object

The open() function returns a file object that is used to perform operations.

Closing Files

file.close()

Using with Statement (Best Practice)

Automatically closes the file.

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

Key Points

• Always close files after use
• Use with to avoid memory leaks

---

• Reading Files

read() Method

Reads the entire file.

read() Method

//Reads the entire file.

with open("example.txt", "r") as file:
    content = file.read()
    print(content)

readline() Method

//Reads one line at a time.

with open("example.txt", "r") as file:
    line = file.readline()
    print(line)

readlines() Method

//Reads all lines into a list.

with open("example.txt", "r") as file:
    lines = file.readlines()
    print(lines)

//Reading Line by Line

with open("example.txt", "r") as file:
    for line in file:
        print(line.strip())

---

• Writing Files

write() Method

//Writes data to a file.

with open("example.txt", "w") as file:
    file.write("Hello Python")

writelines() Method

lines = ["Line 1\n", "Line 2\n"]with open("example.txt", "w") as file:
    file.writelines(lines)

//Appending Data

with open("example.txt", "a") as file:
    file.write("\nNew Line")

Overwriting Files

• Using "w" mode deletes existing content
• Use carefully to avoid data loss

---

• Working with File Modes

File modes define how a file is opened.

Mode	Description
r	Read (default)
w	Write (overwrite)
a	Append
b	Binary mode
r+	Read and write
w+	Write and read
a+	Append and read

---

Examples

("file.txt", "w")# Append mode
open("file.txt", "a")

//Binary Mode Example

with open("image.jpg", "rb") as file:
    data = file.read()

---

Conclusion

File handling is a crucial skill in Python programming, as it enables programs to interact with external data stored on a system. By learning how to open, read, write, and manage files, learners can build applications that store and process real-world data efficiently.

Understanding file modes and best practices like using the with statement ensures safe and efficient file operations. Mastering file handling is essential for advanced topics such as data analysis, web development, and automation.

This module provides a strong foundation for working with files, which is a key requirement in most real-world Python applications.