What is a file object?

A File object is an abstraction representing a file in Python. It provides a way to interact with the file, allowing you to open, read, write, and manage the cursor (position for reading/writing).

It is a low-level interface for working with files in the operating system.

File objects are created when calling the built-in function open().

Main modes of working with files:

• 'r' - read (default)
• 'w' - write (overwrites the file or creates a new one)
• 'a' - append (write at the end of the file)
• 'x' - exclusive creation (creates a file but raises an error if it already exists)
• 'b' - binary mode
• 't' - text mode (default)
• '+' - update (reading and writing)

It is recommended to use a context manager (with open(...)) for automatic closing of the file object.

# Example of opening a file for reading
with open('my_file.txt', 'r') as file:
    content = file.read()
    # ... work with content

# Example of opening a file for writing
with open('new_file.txt', 'w') as file:
    file.write('Hello, world!\n')
    # ... write data

Main methods of the file object:

• read(): reads the entire file or a specified number of bytes/characters.
• readline(): reads one line.
• readlines(): reads all lines into a list.
• write(string): writes a string to the file.
• writelines(list_of_strings): writes a list of strings.
• seek(offset, whence): moves the cursor in the file. whence can be 0 (start), 1 (current position), 2 (end).
• tell(): returns the current cursor position.
• close(): closes the file object (automatically when using with).

File objects in text mode ('t') handle string encoding, while in binary mode ('b') they work with bytes.