How to process Python files

File handling is an important part of any web application.

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

File processing

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

The open() function has two parameters: file name and mode.

There are four different ways (modes) of opening files:

• "r" - read - default. Open the file for reading, and report an error if the file does not exist.

• "a" - Append - Opens the file for appending, or creates the file if it does not exist.

• "w" - write - Opens the file for writing, or creates the file if it does not exist.

• "x" - Create - Creates the specified file, returning an error if the file exists.

Additionally, you can specify whether the file should be processed as binary or text mode.

• "t" - Text - Default value. Text mode.

• "b" - Binary - Binary mode (e.g. image).

Syntax

Additionally, you can specify whether the file should be processed as binary or text mode:

f = open("demofile.txt")

The above code is equivalent to:

f = open("demofile.txt", "rt")

Because "r" (read) and "t" (text) are the default values, there is no need to specify them.

Note: Please make sure the file exists or you will receive an error message.

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