Tag 16: r/w

Program.cs

using System;
using System.Collections.Generic;
using System.IO;

namespace person
{
    class Person
    {
        public Person(string nachname, string vorname)
        {
            this.Vorname = vorname;
            this.Nachname = nachname;
        }

        public string Vorname { get; set; }
        public string Nachname { get; set; }

        public override string ToString()
        {
            return $"{Nachname}|{Vorname}";
        }
    }

    class Personen
    {
        private List<Person> li = new List<Person>();

        public Personen(string file, string mode)
        {
            switch (mode)
            {
                case "read":
                    readFile(file);
                    break;
                case "write":
                    writeFile(file);
                    break;
                case "append":
                    appendFile(file);
                    break;
                default:
                    Console.WriteLine("Error: Unknown mode.");
                    break;
            }
        }

        public void addPerson(string nachname, string vorname)
        {
            this.li.Add(new Person(nachname, vorname));
        }

        public void readFile(string file)
        {   
            if (!File.Exists(file))
            {
                Console.WriteLine("Error: File can not be read.");
                return;
            }

            FileStream fs = null;
            StreamReader sr = null;
            string[] field;

            try
            {
                fs = new FileStream(file, FileMode.Open, FileAccess.Read);
                sr = new StreamReader(fs);
 
                while (sr.Peek() != -1)
                {
                    field = sr.ReadLine().Split('|');
                    this.li.Add(new Person(field[0], field[1]));
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
            }
            finally
            {
                if (sr != null)
                    sr.Close();
                if (fs != null)
                    fs.Close();
            }
        }

        public void writeFile(string file)
        {
            if (this.li.Count == 0)
            {
                Console.WriteLine("Error: Empty list.");
                return;
            }

            FileStream fs = null;
            StreamWriter sw = null;

            try
            {
                fs = new FileStream(file, FileMode.Create, FileAccess.Write);
                sw = new StreamWriter(fs);
                foreach (var p in this.li)
                    sw.WriteLine(p.ToString());
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
            }
            finally
            {
                if (sw != null)
                    sw.Close();
                if (fs != null)
                    fs.Close();
            }
        }

        public void appendFile(string file)
        {
            if (this.li.Count == 0)
            {
                Console.WriteLine("Error: Empty list.");
                return;
            }

            FileStream fs = null;
            StreamWriter sw = null;

            try
            {
                fs = new FileStream(file, FileMode.Append, FileAccess.Write);
                sw = new StreamWriter(fs);
                foreach (var p in this.li)
                    sw.WriteLine(p.ToString());
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
            }
            finally
            {
                if (sw != null)
                    sw.Close();
                if (fs != null)
                    fs.Close();
            }
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            var f = File.Create("/tmp/foo.txt");
            f.Close();
            
            var p = new Personen("/tmp/foo.txt", "read");
            p.addPerson("mustermann", "max");
            p.addPerson("d", "john");
            p.writeFile("/tmp/foo.txt");
            p.addPerson("gandhi", "mahatma");
            p.appendFile("/tmp/foo.txt");

            string[] lines = File.ReadAllLines("/tmp/foo.txt");
            foreach (var s in lines)
                Console.WriteLine(s);

            Console.ReadKey();
        }
    }
}