Arraylist Duplicar Un Archivo De Texto - Ejercicio De Programacion C# Sharp

// Importing necessary namespaces for file I/O and ArrayList
using System; // For basic functionalities like Console
using System.Collections; // For using the ArrayList class
using System.IO; // For file input and output

class Program
{
    static void Main(string[] args)
    {
        // File paths for input and output text files
        string inputFile = "input.txt";  // Path to the input file
        string outputFile = "output.txt"; // Path to the output file

        // Check if the input file exists before proceeding
        if (File.Exists(inputFile))
        {
            // Create an ArrayList to store the lines from the input file
            ArrayList lines = new ArrayList();

            // Reading all lines from the input file and adding them to the ArrayList
            string[] fileLines = File.ReadAllLines(inputFile);
            foreach (string line in fileLines)
            {
                lines.Add(line); // Adding each line to the ArrayList
            }

            // Reversing the order of lines in the ArrayList
            lines.Reverse();

            // Writing the reversed lines to the output file
            File.WriteAllLines(outputFile, (string[])lines.ToArray(typeof(string)));

            Console.WriteLine("The lines have been reversed and written to the output file.");
        }
        else
        {
            // If the input file does not exist, display an error message
            Console.WriteLine("Input file does not exist.");
        }
    }
}

 Salida

If the input file (input.txt) contains the following lines:
Line 1
Line 2
Line 3
Line 4

After running the program, the output file (output.txt) will contain:
Line 4
Line 3
Line 2
Line 1

Error Handling:
Input file does not exist.