CODEWITHSUNDEEP
c#
scylla
scylla

Reputation: 65

Opening text files in C# application

I'm still a beginner when it comes to programming and this is a small application I did following a C# tutorial. 

private void viewImagesToolStripMenuItem_Click(object sender, EventArgs e)
     {

string openedfile = "";

        openfd.Title = "Insert a text file";
        openfd.InitialDirectory = "C:";
        openfd.FileName = "";
        openfd.Filter = "text files|*.txt|word documents|*.doc|allfiles|*.*";


        if (openfd.ShowDialog() == DialogResult.Cancel)

        {
            MessageBox.Show("Operation canceled");
        }

        if (openfd.ShowDialog() != DialogResult.Cancel)

        {
            openedfile = openfd.FileName;
            richTextBox1.LoadFile(openedfile,RichTextBoxStreamType.PlainText);
        }

While doing this I noticed that if I change the same application's code order just 2 lines- 

   string openedfile = "";
   openedfile = openfd.FileName;

like below It will throw me an error like this when debugging - Empty path name is not legal. 

    private void openToolStripMenuItem_Click(object sender, EventArgs e)
    {


        openfd.Title = "Insert a text file";
        openfd.InitialDirectory = "C:";
        openfd.FileName = "";
        openfd.Filter = "text files|*.txt|word documents|*.doc|allfiles|*.*";

        **string openedfile = "";
        openedfile = openfd.FileName;**


        if (openfd.ShowDialog() == DialogResult.Cancel)

        {
            MessageBox.Show("Operation canceled");
        }

        if (openfd.ShowDialog() != DialogResult.Cancel)

        {

            richTextBox1.LoadFile(openedfile,RichTextBoxStreamType.PlainText);
        }

Isn't there a way to understand errors in these type situations. What is the specific order of coding an application like this?

Upvotes: 1

Views: 410

Answers (4)

Amit Mittal
Amit Mittal

Reputation: 1127

I generally Prefer this:

private void viewImagesToolStripMenuItem_Click(object sender, EventArgs e)
 {

    DialogResult dr=openfd.ShowDialog();
    if(dr==DialogResult.Ok)
    {   
       richTextBox1.LoadFile(openfd.FileName,RichTextBoxStreamType.PlainText);           
    }
    else
    {
      MessageBox.Show("No file Selected!!");
    }

}

Upvotes: 0

Sayse
Sayse

Reputation: 43300

I'm going to go ahead and guess that the problem is the openfd.FileName call outside of the if block (and also before its retrieved), while the if block is still being exectuted the openfd is "left open" if you like, so you can retrieve its result.

When you have left, the if block, you are effectively saying you are done with this dialog, please continue.

In your code you are showing multiple dialogs with multiple calls to show dialog also, consider the following.

    if (openfd.ShowDialog() == DialogResult.OK)
    {
        pictureBox1.Image = Image.FromFile(openfd.FileName);
    }
    else
    {
        MessageBox.Show("Operation canceled");
    }

(Changed to use dialogresult.ok as this is more than likely the result you wish to receive from the dialog)

Update

With respect to your current applcation, each call to ShowDialog() is opening a new dialog. Consider it similar to 

MessageBox.Show("woo");
MessageBox.Show("hoo");

in the above, when the first messagebox is closed, it will close the dialog and move onto handling the second message box (the next line of code), with your 

if (openfd.ShowDialog() != DialogResult.Cancel)

Your showdialog is still in use by the if statement so it is deemed to be still in use and not disposed of straight away. When the if statement is finished with, your dialog will then be deemed to be ok to dispose

Also, the error in your application is not to do with the filename path, its trying to load in a file that has no name

Upvotes: 1

Ratna
Ratna

Reputation: 2319

well, the idea is simple you cannot use a variable that has been not initialized. in your case sm thing same is happening. In your first code openedfile = openfd.FileName; is being executed after the dialouge has been shown. Thus the file name comes correctly. But in the second openedfile = openfd.FileName; is getting initialized before the dilogue has been shown. Since there is no dialogue the name is null, hence it gives error.

Note. I have used initialized word not in tecnical manner.

Upvotes: 2

Hans Kesting
Hans Kesting

Reputation: 39284

The line openedfile = openfd.FileName; will not bind the two variables, it will copy the value that openfd.FileName has at this moment into openedfile.

In your second example the user has not yet selected a file at that moment, so this value is still empty (""). The value that is selected later in openfd will be ignored.

EDIT which is why you get the error Empty path name is not legal.

Upvotes: 1

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