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using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.IO;
using System.Linq;

namespace Notizblock_2018_03_13
{
    public partial class Notizblock : Form
    {


        public Notizblock()
        {
            InitializeComponent();
            lb_1.Text = DateTime.Now.ToLongDateString();
        }


        private void lb_1_Click(object sender, EventArgs e)
        {

        }

        private void Notizblock_Load(object sender, EventArgs e)
        {
            loadtxt();
        }

        private void Notizblock_FormClosing(object sender, FormClosingEventArgs e)
        {
            savetxt();
            File.Delete("C:/Users/xxx/source/repos/Notizblock_2018_03_13/Notizblock_2018_03_13/bin/Debug/notes.txt");
        }

        void loadtxt()
        {
            //LADEN
            if (System.IO.File.Exists("C:/Users/xxx/source/repos/Notizblock_2018_03_13/Notizblock_2018_03_13/bin/Debug/notes.txt"))
            {
               
            }
            else
            {
                File.Create("C:/Users/xxx/source/repos/Notizblock_2018_03_13/Notizblock_2018_03_13/bin/Debug/notes.txt");
            }
            System.IO.StreamReader sr = new System.IO.StreamReader("C:/Users/xxx/source/repos/Notizblock_2018_03_13/Notizblock_2018_03_13/bin/Debug/notes.txt");
            tb_1.Text = sr.ReadToEnd();
            sr.Close();
        }

        void savetxt()
        {
            //SPEICHERN
            StreamWriter sw = new System.IO.StreamWriter("C:/Users/xxx/source/repos/Notizblock_2018_03_13/Notizblock_2018_03_13/bin/Debug/notes.txt");
            sw.WriteLine(tb_1.Text);
            sw.Close();
        }

        private void tb_1_TextChanged(object sender, EventArgs e)
        {

        }

        private void eigenschaftenToolStripMenuItem_Click(object sender, EventArgs e)
        {

        }

        private void dateiToolStripMenuItem_Click(object sender, EventArgs e)
        {

        }

        private void öffnenToolStripMenuItem_Click(object sender, EventArgs e)
        {
            string Pfad = "";
            //Öffnet Dialogfeld
            OpenFileDialog
                openFileDialog1 = new OpenFileDialog();
            openFileDialog1.Filter = "txt files (*.txt)|*.txt|All files (*.*)|*.*";
            if (openFileDialog1.ShowDialog() == DialogResult.OK)
                Pfad = openFileDialog1.FileName;
            //Liest Datei und Lädt
            System.IO.StreamReader sr = new System.IO.StreamReader(Pfad);
            tb_1.Text = sr.ReadToEnd();
            sr.Close();
        }

        private void speichernToolStripMenuItem_Click(object sender, EventArgs e)
        {
            savetxt();
        }

        private void tb_1_KeyDown(object sender, KeyEventArgs e)
        {
            savetxt();
        }

        private void neuToolStripMenuItem_Click(object sender, EventArgs e)
        {

        }
    } 
}					

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File.Create("C:/Users/xxx/source/repos/Notizblock_2018_03_13/Notizblock_2018_03_13/bin/Debug/notes.txt");					

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using (File.Create("C:/Users/xxx/source/repos/Notizblock_2018_03_13/Notizblock_2018_03_13/bin/Debug/notes.txt"))					

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string path = Path.Combine(Application.StartupPath, "notes.txt");					

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string path = Path.Combine(Application.StartupPath, "MyTextFiles", "notes.txt");