Python File Handling

Python File Handling

File handling is an essential part of any web application or software project. Whether you need to process uploaded files, read configuration settings, log errors, or save user data, you must know how to interact with the file system.

Python has several built-in functions for creating, reading, updating, and deleting files.

The open() Function

The key function for working with files in Python is the open() function.

The open() function takes two primary parameters:

1. filename: The name (and path) of the file you want to open.
2. mode: A string specifying the mode in which the file is opened.

File Opening Modes

There are four different methods (modes) for opening a file:

• "r" - Read - Default value. Opens a file for reading. It will return an error if the file does not exist.
• "a" - Append - Opens a file for appending. It will create the file if it does not exist, and add new data to the end of the file.
• "w" - Write - Opens a file for writing. It will overwrite any existing content, and create the file if it does not exist.
• "x" - Create - Creates the specified file. It returns an error if the file already exists.

Text vs. Binary

In addition to the operational mode, you can specify if the file should be handled as text or binary mode:

• "t" - Text - Default value. Used for standard text files (e.g., .txt, .csv).
• "b" - Binary - Used for binary mode (e.g., images like .jpg or .png, audio, or compiled data).

Basic Syntax

To open a file for reading, it is enough to specify the name of the file. By default, Python assumes "rt" (Read and Text).

// This is the exact same as open("demofile.txt", "rt")
f = open("demofile.txt")

Because "r" for read, and "t" for text are the default values, you do not need to specify them unless you want to be explicit for code readability.