Windows Form form application, build a notepad reference code that focuses on open, save, and Save As

// When clicked to open
        private string files; // Create a member variable to store the open path
        private void open OToolStripMenuItem_Click (object sender, EventArgs e)
        {
            //openFileDialog1.Filter = "Text file | * txt | Video file | * avi; * jpg"; // filter create a filter
            //openFileDialog1.ShowDialog ();
            DialogResult isok = openFileDialog1.ShowDialog ();
            if (isok == DialogResult.OK) // Determine if the open button was clicked
            {
                string filename = openFileDialog1.FileName; // Get the file path, the file path is stored in FileName
                // Use stream for file reading
                StreamReader sr = new StreamReader (filename); // Build a streamreader object sr with the file path as a parameter
                textBox1.Text = sr.ReadToEnd (); // readtoend method, read the file completely
                sr.Close (); // The stream must be closed after running out
                files = filename;
            }
// when clicking the save as button
        private void holds sToolStripMenuItem_Click (object sender, EventArgs e)
        {
            saveFileDialog1.Filter = "Text file | * .txt"; // File format to save. Filter file filter
            DialogResult isok = saveFileDialog1.ShowDialog (); // Whether to click the save button
            if (isok == DialogResult .OK)
            {
                string filename = saveFileDialog1.FileName;
                StreamWriter sw = new StreamWriter (filename);
                sw.Write (textBox1.Text);
                sw.Close (); // Be sure to close the stream
            }
            MessageBox.Show (saveFileDialog1 .FileName);
        }

        // When the save button is clicked
        private void Save as AToolStripMenuItem_Click (object sender, EventArgs e)
        {
            if (files == null)
            {
                DialogResult baocun = saveFileDialog1.ShowDialog ();
                if (baocun == DialogResult.OK)
                {
                    string filename = saveFileDialog1.FileName;
                    StreamWriter sw = new StreamWriter (filename);
                    sw.Write (textBox1.Text);
                    sw.Close ();
                }
            }
            else
            {
                StreamWriter sw = new StreamWriter (files);
                sw.Write (textBox1.Text);
                sw.Close ();
            }
        }
  // When clicking on the color
        private void color ToolStripMenuItem_Click (object sender, EventArgs e)
        {
            //colorDialog1.ShowDialog();//To display the color dialog box, the dialog box to be displayed has the common property of showdialog. . colorDialog1.ShowDialog () will have a return value and accept it with the dialogresult enum type
            DialogResult dr = colorDialog1.ShowDialog ();
            if (dr == DialogResult .OK) // Determine whether to click the OK button
            {
                this.BackColor = colorDialog1.Color; // If you just write this code and click Cancel after selecting the color, it will default to a black in the system
            }
            
        }
        // click the file browser to get the path
        private void file browser ToolStripMenuItem_Click (object sender, EventArgs e)
        {
            DialogResult dr = folderBrowserDialog1.ShowDialog (); // Return value when accepting the punch file path
            if (dr == DialogResult .OK)
            {
                MessageBox.Show (folderBrowserDialog1.SelectedPath); // selectedpath gets the attributes of the path
            }
        }
  // When click New
        private void new NToolStripMenuItem_Click (object sender, EventArgs e)
        {
            if (textBox1 .Text .Length> 0)
            {
                saveFileDialog1.ShowDialog ();
                DialogResult dr = new DialogResult ();
                if (dr == DialogResult.OK)
                {
                    string filename = saveFileDialog1.FileName;
                    StreamWriter sw = new StreamWriter (filename);
                    sw.Write (textBox1.Text);
                    sw.Close ();
                }
                else
                {
                    textBox1.Text = "";
                }
            }
        } 

Windows Form form application, build a notepad reference code that focuses on open, save, and Save As