File Splitter - C# Programming Exercise

// Import the necessary namespaces for file handling and system operations
using System; // System namespace for basic input/output operations
using System.IO; // For file handling functions like FileStream
using System.Text; // For encoding and byte handling

class FileSplitter // Main class for the file splitting program
{
    static void Main(string[] args) // Entry point of the program
    {
        // Check if two arguments are provided (the file path and the size)
        if (args.Length != 2) // Check if the number of arguments is incorrect
        {
            Console.WriteLine("Usage: FileSplitter  "); // Display usage instructions
            return; // Exit the program if arguments are not correct
        }

        string fileName = args[0]; // Get the file name from the first argument
        int chunkSize; // Declare a variable for chunk size
        bool isNumeric = Int32.TryParse(args[1], out chunkSize); // Try to convert the second argument to an integer for the chunk size

        // Validate that the chunk size is a positive number
        if (!isNumeric || chunkSize <= 0) // If the chunk size is not valid or non-positive
        {
            Console.WriteLine("Error: Chunk size must be a positive number."); // Inform the user about the error
            return; // Exit the program if the chunk size is invalid
        }

        // Check if the file exists
        if (!File.Exists(fileName)) // If the file doesn't exist
        {
            Console.WriteLine("Error: The file does not exist."); // Inform the user about the missing file
            return; // Exit the program if the file is missing
        }

        try
        {
            // Open the source file for reading
            using (FileStream inputFile = new FileStream(fileName, FileMode.Open, FileAccess.Read)) // Open the file in read-only mode
            {
                long fileLength = inputFile.Length; // Get the length of the file in bytes
                int chunkCount = (int)(fileLength / chunkSize); // Calculate how many full chunks will be created
                if (fileLength % chunkSize != 0) chunkCount++; // If there is a remainder, add one more chunk

                byte[] buffer = new byte[chunkSize]; // Create a buffer to store chunks of the file
                int bytesRead; // Variable to store the number of bytes read at a time

                // Loop through the file and create the chunks
                for (int i = 0; i < chunkCount; i++) // Loop over each chunk
                {
                    string outputFileName = $"{fileName}.{i + 1:D3}"; // Generate the output file name (e.g., myFile.exe.001, myFile.exe.002, etc.)

                    // Open a new file to write the current chunk
                    using (FileStream outputFile = new FileStream(outputFileName, FileMode.Create, FileAccess.Write)) // Open the output file in write mode
                    {
                        // Calculate how many bytes to read for the current chunk
                        bytesRead = inputFile.Read(buffer, 0, chunkSize); // Read the next chunk of the file

                        // Write the chunk to the output file
                        outputFile.Write(buffer, 0, bytesRead); // Write the read bytes to the new file
                    }

                    Console.WriteLine($"Created chunk {outputFileName} with {bytesRead} bytes."); // Notify the user about the chunk created
                }
            }

            Console.WriteLine("File split complete."); // Inform the user that the splitting is complete
        }
        catch (Exception ex) // Catch any exceptions that occur during the file handling
        {
            Console.WriteLine($"An error occurred: {ex.Message}"); // Display the error message
        }
    }
}