Question

I’m a complete beginner to this language and am currently trying to create a simple text editing application, but am getting the above error when trying to open a file.
The code’s below, any help would be much appreciated.

private void mnuOpen_Click(object sender, EventArgs e)
    {
        string chosenFile = "";

        openFD.Title = "Select a text file";
        openFD.InitialDirectory = System.Environment.GetFolderPath(Environment.SpecialFolder.Personal);
        openFD.FileName = "Choose a file..";
        openFD.Filter = "Text Files|*.txt|All Files|*.*";

        if (openFD.ShowDialog() != DialogResult.Cancel)
        {
            contentBox.LoadFile(chosenFile, RichTextBoxStreamType.PlainText);
        }
    }

The exception itself occurs here:

contentBox.LoadFile(chosenFile, RichTextBoxStreamType.PlainText);

Answer 1

You need to set chosenFile to the name of the file selected in the OpenFileDialog control:

private void mnuOpen_Click(object sender, EventArgs e)
{
    string chosenFile = "";

    openFD.Title = "Select a text file";
    openFD.InitialDirectory = System.Environment.GetFolderPath(Environment.SpecialFolder.Personal);
    openFD.FileName = "Choose a file..";
    openFD.Filter = "Text Files|*.txt|All Files|*.*";

    if (openFD.ShowDialog() != DialogResult.Cancel)
    {
        // Assign the selected filename to chosenFile
        chosenFile = openFD.FileName;
        contentBox.LoadFile(chosenFile, RichTextBoxStreamType.PlainText);
    }
}