This program provides functionality for encoding and decoding text files using custom algorithms:

Purpose: Encodes or decodes the content of a file based on user input. How It Works: User Interaction:

The user selects encoding ('C') or decoding ('D') and provides the names of input and output files. Encoding:

For digits: Each digit is incremented by a counter (modulo 10). For letters: A character shift is applied based on the previous character's value. Adjustments ensure the result stays within valid alphabetical ranges. Other characters are written as-is. Decoding:

Reverse logic is applied to decode digits and letters back to their original values, ensuring proper handling of character boundaries. File Operations:

The program opens the specified files, processes them with encode or decode, and writes the output. It reports errors for issues like file access. Output:

Prints the total number of characters processed.