Question

I’m new to programming and I’m starting to create a simple notepad, with only 4 buttons (Open, Save, New and Font).

If I open or save I’m getting an error. This is my code:

        //Declare save as a new SaveFileDailog
        SaveFileDialog save = new SaveFileDialog();
        //Declare filename as a String equal to the SaveFileDialog's FileName
        String filename = save.FileName;
        //Declare filter as a String equal to our wanted SaveFileDialog Filter
        String filter = "Text Files|*.txt|All Files|*.*";
        //Set the SaveFileDialog's Filter to filter
        save.Filter = filter;
        //Set the title of the SaveFileDialog to Save
        save.Title = "Save";
        //Show the SaveFileDialog
        if (save.ShowDialog(this) == DialogResult.OK)
        {
            //Write all of the text in txtBox to the specified file
            System.IO.File.WriteAllText(filename, textBox1.Text);
        }
        else
        {
            //Return
            return;
        }//Declare save as a new SaveFileDailog
        SaveFileDialog save = new SaveFileDialog();
        //Declare filename as a String equal to the SaveFileDialog's FileName
        String filename = save.FileName;
        //Declare filter as a String equal to our wanted SaveFileDialog Filter
        String filter = "Text Files|*.txt|All Files|*.*";
        //Set the SaveFileDialog's Filter to filter
        save.Filter = filter;
        //Set the title of the SaveFileDialog to Save
        save.Title = "Save";
        //Show the SaveFileDialog
        if (save.ShowDialog(this) == DialogResult.OK)
        {
            //Write all of the text in txtBox to the specified file
            System.IO.File.WriteAllText(filename, textBox1.Text);
        }
        else
        {
            //Return
            return;
        }

Update

Here is the error:

Error: ArgumentException was unhandled.
Empty path name is not legal

I get this if I open a text file. Then it highlighted this line code:
textBox1.Text=System.IO.File.ReadAllText(filename,System.Text.Encoding.Default).

And if I save nothing happens.

Answer 1

I expect you should be reading the filename after the user has used the dialog:

System.IO.File.WriteAllText(save.FileName, textBox1.Text);

Also – SaveFileDialog is IDisposable, so you should be “using” it…

using (SaveFileDialog save = new SaveFileDialog())
{
    // your code that involves "save"
}