why can't i correctly access text in textbox in another form

Question

lotrsimp12345 37 Posting Pro in Training

13 Years Ago

I have set the textbox to public so that another form can access it but when i run it in debug mode with the following line it gives me exception so it doesn't store correct directory.
For example:
If I enter D:\newfolder it gives me D:\\newfolder. Why does it add the extra \.

Here's the exception:
An exception 'Microsoft.VisualStudio.Debugger.Runtime.CrossThreadMessagingException' occurred

Here's the line where the exception occurs.

Choose is a class in the same namespace as the method which contains this string.
The method is in a different class than the choose class.
txtbxTargetDir is the name of the textbox.

string targetPath = StaticFormInstances.choose.txtbxTargetDir.Text;

Edited 13 Years Ago by lotrsimp12345 because: n/a

3 Contributors
13 Replies
810 Views
23 Hours Discussion Span
Latest Post 13 Years Ago Latest Post by Geekitygeek

All 13 Replies

finito 46 Nearly a Posting Virtuoso

13 Years Ago

try

string targetPath ="@" + StaticFormInstances.choose.txtbxTargetDir.Text;

Edited 13 Years Ago by finito because: n/a

Geekitygeek 480 Nearly a Posting Virtuoso

13 Years Ago

the extra backslash is an escape character; it is used at the start of an escape sequence. An escape sequence is a series of characters which the compiler reads and converts into somethign else. For instance \n becomes a newline character. To tell the compiler that the '\' is to be treated as a plain character you have to escape it. Hence the double \. If you display the string in a textbox or a messagebox it should only show a single one (the debugger will show you the extra one when you use a watch).
The trick of using an '@' wont work the way shown above. It CAN be used to declare a literal string. eg string str = @"this backslash \ is just a literal character"; . By putting an @ before the string you tell the compiler that none of the characters are escape sequences, they are just plain old characters :)

finito 46 Nearly a Posting Virtuoso

13 Years Ago

label1.Text = label1.Text.Substring(0, label1.Text.IndexOf(@"\")) + label1.Text.Substring(label1.Text.IndexOf(@"\")+1, label1.Text.Length-(label1.Text.IndexOf(@"\"))-1);

Here this should give you a fix.

It will basically remove one of the slashes.

Edited 13 Years Ago by finito because: n/a

finito 46 Nearly a Posting Virtuoso

13 Years Ago

hmm, what does the targetPath equal to right before the line of error?

try

MessageBox.Show(targetPath);

right before the line error.

Edited 13 Years Ago by finito because: n/a

Reply to this topic

Be a part of the DaniWeb community

We're a friendly, industry-focused community of developers, IT pros, digital marketers, and technology enthusiasts meeting, networking, learning, and sharing knowledge.

lotrsimp12345 37 Posting Pro in Training · Answer 1 · 2010-07-20T22:06:46+00:00

that doesn't work, it just adds the @ sign in front of the string and still keeps 2 \\

lotrsimp12345 37 Posting Pro in Training · Answer 2 · 2010-07-20T22:38:36+00:00

I still get the same exception. I think its because I am trying to access it in multiple forms. Maybe???
Btw I have each form set up as static so that I can add back button to it.

Heres the exception:
at Microsoft.VisualStudio.Debugger.Runtime.Main.ThrowCrossThreadMessageException(String formatString) at System.Windows.Forms.SafeNativeMethods.GetWindowTextLength(HandleRef hWnd) at System.Windows.Forms.Control.get_WindowText() at System.Windows.Forms.TextBoxBase.get_WindowText() at System.Windows.Forms.Control.get_Text() at System.Windows.Forms.TextBox.get_Text()

Please help.

lotrsimp12345 37 Posting Pro in Training · Answer 3 · 2010-07-20T23:18:25+00:00

Here is my code

public partial class InstallingDlls : Form
    {
        public InstallingDlls()
        {
            InitializeComponent();
            bckgrdInstallDll.RunWorkerAsync();
        }

        private void bckgrdInstallDll_DoWork(object sender, DoWorkEventArgs e)
        {
            //string text = StaticFormInstances.choose.txtbxTargetDir.Text.Substring(0, StaticFormInstances.choose.txtbxTargetDir.Text.IndexOf(@"\")) + StaticFormInstances.choose.txtbxTargetDir.Text.Substring(StaticFormInstances.choose.txtbxTargetDir.Text.IndexOf(@"\") + 1, StaticFormInstances.choose.txtbxTargetDir.Text.Length - (StaticFormInstances.choose.txtbxTargetDir.Text.IndexOf(@"\")));


            string fileName = "test.txt";
            string targetPath = StaticFormInstances.choose.txtbxTargetDir.Text;
            string sourcePath = @"\\il93fil48\3GSM\release\testapplication_REL_01_00_09\bin";

            //Use Path Class to manipulate file and directory paths
            string sourceFile = System.IO.Path.Combine(sourcePath, fileName);
            string destFile = System.IO.Path.Combine(targetPath, fileName);

            //Create a new target folder if it doesn't exist
            if (!System.IO.Directory.Exists(targetPath))
            {
                System.IO.Directory.CreateDirectory(targetPath);
            }


            if (System.IO.Directory.Exists(sourcePath))
            {
                string[] files = System.IO.Directory.GetFiles(sourcePath);

                //calculate total number of files in source
                int totalNumberOfFiles = files.Length;

                //current file number
                int fileNumber = 0;

                //copy the files and overwrite destination files if they already exist
                foreach (string s in files)
                {
                    //increase file number by 1
                    fileNumber++;

                    //Use static Path methods to extract only the file name from the path.
                    fileName = System.IO.Path.GetFileName(s);
                    destFile = System.IO.Path.Combine(targetPath, fileName);
                    System.IO.File.Copy(s, destFile, true);

                    //calculate progess out of base of 100
                    int ProgressPercentage = (fileNumber/totalNumberOfFiles)*100;

                    //update the progress bar
                    bckgrdInstallDll.ReportProgress(ProgressPercentage);
                }
            }
            else
            {
                Console.WriteLine("Source path does not exist");
            }
        }

        private void bckgrdInstallDll_ProgressChanged(object sender, ProgressChangedEventArgs e)
        {
            prgBarDll.Value = e.ProgressPercentage;
        }

        private void bckgrdInstallDll_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            StaticFormInstances.database = new Database();
            StaticFormInstances.database.Show();
            StaticFormInstances.dll.Hide();
        }
    }

Geekitygeek 480 Nearly a Posting Virtuoso · Answer 4 · 2010-07-20T23:18:38+00:00

The error you are getting is a thread related exception. Can you post your code so we can see what it is you are doing.

Geekitygeek 480 Nearly a Posting Virtuoso · Answer 5 · 2010-07-20T23:20:31+00:00

If you are accessing controls from a thread you will need to invoke a delegate. You cannot directly access controls form another thread. Check out the example here and see if that helps any.

lotrsimp12345 37 Posting Pro in Training · Answer 6 · 2010-07-20T23:24:32+00:00

I am not trying to update my value in another thread, I am trying to access it.

Geekitygeek 480 Nearly a Posting Virtuoso · Answer 7 · 2010-07-20T23:43:46+00:00

The principle is the same; you need to invoke a delegate method to retreive the value as you cannot directly access the control.
The example accepts a string as input but returns no value. Heres part one of reversing the process:

// Returns the textbox text.
private string UpdateText()
{
  // Send textbox text back to calling method
  return m_TextBox.Text;
}

If you have troubles with the rest, post what you ahve and we'll guide you through it

lotrsimp12345 37 Posting Pro in Training · Answer 8 · 2010-07-21T00:00:16+00:00

It doesn't seem to work. Compile error.

namespace Welcome
{
    public delegate string ReturnText();
    public partial class InstallingDlls : Form
    {
        public InstallingDlls()
        {
            InitializeComponent();
            bckgrdInstallDll.RunWorkerAsync();
        }

        private void bckgrdInstallDll_DoWork(object sender, DoWorkEventArgs e)
        {
            StaticFormInstances.dll.Invoke(new ReturnText(this.UpdateText));

            string fileName = "test.txt";
            string targetPath = StaticFormInstances.choose.txtbxTargetDir.Text;
            string sourcePath = @"\\il93fil48\3GSM\release\testapplication_REL_01_00_09\bin";

            //Use Path Class to manipulate file and directory paths
            string sourceFile = System.IO.Path.Combine(sourcePath, fileName);
            string destFile = System.IO.Path.Combine(targetPath, fileName);

            //Create a new target folder if it doesn't exist
            if (!System.IO.Directory.Exists(targetPath))
            {
                System.IO.Directory.CreateDirectory(targetPath);
            }


            if (System.IO.Directory.Exists(sourcePath))
            {
                string[] files = System.IO.Directory.GetFiles(sourcePath);

                //calculate total number of files in source
                int totalNumberOfFiles = files.Length;

                //current file number
                int fileNumber = 0;

                //copy the files and overwrite destination files if they already exist
                foreach (string s in files)
                {
                    //increase file number by 1
                    fileNumber++;

                    //Use static Path methods to extract only the file name from the path.
                    fileName = System.IO.Path.GetFileName(s);
                    destFile = System.IO.Path.Combine(targetPath, fileName);
                    System.IO.File.Copy(s, destFile, true);

                    //calculate progess out of base of 100
                    int ProgressPercentage = (fileNumber/totalNumberOfFiles)*100;

                    //update the progress bar
                    bckgrdInstallDll.ReportProgress(ProgressPercentage);
                }
            }
            else
            {
                Console.WriteLine("Source path does not exist");
            }
        }

        private void bckgrdInstallDll_ProgressChanged(object sender, ProgressChangedEventArgs e)
        {
            prgBarDll.Value = e.ProgressPercentage;
        }

        private void bckgrdInstallDll_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            StaticFormInstances.database = new Database();
            StaticFormInstances.database.Show();
            StaticFormInstances.dll.Hide();
        }
    }
}

namespace Welcome
{
    public partial class ChooseDirectory : Form
    {
        public ChooseDirectory()
        {
            InitializeComponent();
        }

        private void btnNext_Click(object sender, EventArgs e)
        {
            StaticFormInstances.choose.Hide();
            StaticFormInstances.loc = new Location();
            StaticFormInstances.loc.Show();
        }

        private void btnCancel_Click(object sender, EventArgs e)
        {
            StaticFormInstances.wel.Dispose();
            StaticFormInstances.choose.Dispose();
        }

        private string UpdateText()
        {
            //send textbox text back to calling method
            return StaticFormInstances.choose.txtbxTargetDir.Text;
        }
    }
}

Geekitygeek 480 Nearly a Posting Virtuoso · Answer 9 · 2010-07-21T15:27:35+00:00

Can you post your project? Im having troubles replicating the issue :/
If you click "Use Advanced Editoer" there is an attachments button at the top of the box where you can add a zipped copy of your folder.
If i can run your code i may be ablet o find the problem :)

why can't i correctly access text in textbox in another form

Recommended Answers Collapse Answers

All 13 Replies

Recommended Answers