CBSE 12th Unit 1 - Chapter -2 introduction to files, types of files (Text file, Binary file, CSV file), relative and absolute paths

Introduction to Files

• Files are used to store data persistently on your computer's storage.
• Python provides built-in functions to work with files (e.g., open(), read(), write(), close()).

Types of Files

• Text File:

  • Stores data as plain text characters.
  • Examples: .txt, .py, .html, .md
  • Can be easily read and edited with a text editor.

• Binary File:

  • Stores data in a binary format (a sequence of bytes).
  • Examples: .jpg, .png, .mp3, .exe, .pdf
  • Requires specialized software to open and view.

• CSV File (Comma-Separated Values):

  • Stores data in a tabular format where values are separated by commas.
  • Often used for spreadsheets and databases.
  • Example: .csv

File Handling in Python

Python

# Opening a file in read mode
file = open("my_file.txt", "r")
contents = file.read()
print(contents)
file.close()

# Opening a file in write mode (creates a new file or overwrites existing)
file = open("new_file.txt", "w")
file.write("This is a new line.")
file.close()

File Paths

• Absolute Path:

  • The full path to the file, starting from the root directory of the file system.
  • Example: /Users/username/Documents/my_file.txt

• Relative Path:

  • The path to the file relative to the current working directory.
  • Example: data/my_file.txt (if the file is located in the data folder within the current working directory)

Diagram

                        file system diagram showing absolute and relative paths

Key Points

• open() function:

  • Takes two arguments: the file name and the mode ("r" for reading, "w" for writing, "a" for appending, etc.).
  • Returns a file object that can be used to interact with the file.

• read() method:

  • Reads the contents of the file.

• write() method:

  • Writes data to the file.

• close() method:

  • Closes the file and releases the resources associated with it.

• with statement:

  • A more elegant way to handle files, as it automatically closes the file even if an exception occurs.

Python

with open("my_file.txt", "r") as file:
    contents = file.read()
    print(contents)

Note: This is a basic introduction to file handling in Python. You can explore more advanced topics like reading and writing binary files, working with CSV files using the csv module, and handling file-related exceptions.