File Handling in Python | Text Files | Class 12 Computer Science

Introduction

This tutorial covers file handling in Python, focusing on text files, as outlined in the video by Swati Chawla. Understanding file handling is crucial for managing data efficiently in your Python applications, whether for reading, writing, or modifying text files.

Step 1: Understanding the Need for File Handling

File handling is essential for the following reasons:

• Data Persistence: Saving data beyond the runtime of a program.
• Data Management: Easy retrieval and storage of data.
• Data Sharing: Facilitating data exchange between different programs or users.

Step 2: Types of Files

Familiarize yourself with the main types of files in Python:

• Text Files: Store data in plain text format (e.g., .txt files).
• Binary Files: Store data in binary format (e.g., images, executables).

Step 3: Opening a File

To work with files, you first need to open them using Python's built-in open() function. Here’s how:

• Use the following syntax:

  file = open('filename.txt', 'mode')
  

• Replace 'filename.txt' with your file name and mode with the desired access mode.

Step 4: File Access Modes

Understand the different modes for opening files:

• 'r': Read mode (default).
• 'w': Write mode (overwrites existing data).
• 'a': Append mode (adds data without deleting existing content).
• 'b': Binary mode (used for binary files).

Step 5: Writing Data to a Text File

To write data into a text file:

1. Open the file in write or append mode.
2. Use the write() or writelines() method to add content.

Example:

with open('example.txt', 'w') as file:
    file.write('Hello, World!\n')
    file.writelines(['Line 1\n', 'Line 2\n'])

Step 6: Flushing the Buffer

When writing data, you may want to ensure that all data is written from the buffer to the file immediately. Use the flush() method:

file.flush()

This is useful when you need to ensure data integrity before closing the file.

Step 7: Reading Data from a Text File

To read data from a text file:

1. Open the file in read mode.
2. Use methods like read(), readline(), or readlines().

Example:

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

Step 8: Closing the File

Always close the file after operations to free up system resources. Use:

file.close()

Alternatively, use the with statement, which automatically handles closing the file.

Conclusion

In this tutorial, you learned about file handling in Python, including the need for it, different file types, how to open files, access modes, writing and reading data, and the importance of closing files. Mastering these skills will enhance your ability to manage data in your Python applications effectively. Next, consider practicing by creating your own text files and manipulating their contents using the techniques learned here.