Imitating Console.ReadLine() with a RTB & TXT

I have two controls on a windows form.

rtbOutput = RichTextBox
txtInput = TextBox

When the KeyDown event is triggered, if e.Keycode == Keys.Enter then a combination of a Switch block and if statements are used to process what the user entered in the textbox (txtInput). If for example it equals "exit" then the application will exit: Application.Exit();

If it were another command for example 'time', then "The time is ...." would be appended on a new line of rtbOutput. However how would I create my own version of Console.ReadLine()? For example when the user types 'exit', instead of just exiting the application, a new line is added to rtbOutput: "Are you sure you would like to exit? (Y/N)". Then the user has the option of typing y/n to exit or not exit the application.

This is simple in a Console application.

Code:

---

If(Console.ReadLine() == "exit"){
Console.WriteLine("Are you sure you would like to exit?");
If(Console.ReadLine() == "n"){
return;
}
Application.Exit();
}

---

When it comes to using a richTextBox and a textBox how can I 'Read' the next line the user enters and continue with my if statement, processing the response, just like I would do with a console application?

What exactly is the problem? You have all the pieces

Quote:

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Originally Posted by noahssite

When it comes to using a richTextBox and a textBox how can I 'Read' the next line the user enters and continue with my if statement, processing the response, just like I would do with a console application?

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You can't, unless you have that code executing on a secondary thread.

a little hint: catch the event when the text changes. now, if the character is a carriage return, then read the previous line and use your switch block to determine what that line stated. or even better, use the keydown event args to determine what key was pressed.



example:

Drop a textbox on the form.
View the events of the textbox in the properties window, and double click the KeyDown event to subscribe to the event and for the application to handle that event.

the textbox exposes a string[] array of lines - a collection of lines in the textbox. we need to access the previous line after you hit enter to know what the user wrote.

Then, the code is something like the following:

Code:

---


void textbox1_KeyDown(object sender, KeyEventArgs e)
{
  if (e.KeyData == Keys.Return || e.KeyData = Keys.Enter)
  {
      string previousLine = this.textbox1.Lines[this.textbox1.Lines.Count() - 1];
      // execute your switch statement here, checking the previousLine
  }
}

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now, re-reading your post, I guess you want to determine the answer/response from the user's question that YOU programmatically give?
I guess by using the same method/approach outlined above, you can read what the previous line has (in this case, the example is "are you sure?") then since they pressed enter (the user), then you do your validation there.

does this help?

I was thinking of a few ways of accomplishing this.. One of my major issues is efficiency...

I'm going to work with a separate thread to handle the input of the text box.

I'll post back once I've accomplished my goal (or if I fail..).

EDIT: I think I'm just going to make a thread (like jmc said) that works like Console.ReadLine(), it would wait for the user to enter a new line and then return a value, I'm going to have to read a bit more about threads since I'm not sure how I can make it return a value.. Like I said before I'll post back my progress.

sure but question is, why do you need a thread? what is the reasoning behind it? maybe im missing something? Threads really are used for heavy tasking without blocking the UI.

Quote:

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Originally Posted by Techno

sure but question is, why do you need a thread? what is the reasoning behind it? maybe im missing something? Threads really are used for heavy tasking without blocking the UI.

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Isn't that the point? If I have the If...Then statement on hold waiting for a value to be returned won't it 'pause' the UI? Well that's if I use a loop, which wouldn't be very good. I'm going to try a few things. Whatever comes to my head..

from what I understood and please DO correct me, you are going to be using a textbox for input. textbox does not block the UI thread for input. therefore, no need for a thread.

the solution provided earlier will monitor the user's keypress (again doesnt block the thread) and then you do your conditions in there depending on the keystroke entered and what the functionality of your software is.

you may have switch/if statements but they do not block the thread, not unless you are using some horrendous loop, looping through endlessly, which won't be the case here.

Quote:

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Originally Posted by Techno

from what I understood and please DO correct me, you are going to be using a textbox for input. textbox does not block the UI thread for input. therefore, no need for a thread.

the solution provided earlier will monitor the user's keypress (again doesnt block the thread) and then you do your conditions in there depending on the keystroke entered and what the functionality of your software is.

you may have switch/if statements but they do not block the thread, not unless you are using some horrendous loop, looping through endlessly, which won't be the case here.

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So no more threads! That's going to make it easier.

How do I access a control such as a RichTextBox from a thread it wasn't created on?

EDIT: More specifically what I want is to retrieve the Lines.Length of the RichTextBox.

Follow the CodeBank link in my signature and check out my post on Accessing Controls From Worker Threads. It shows you how to pass data into and get data out of controls from worker threads. A lot of people seem to stumble at the first step: create a method that does what you want without multi-threading. In your case, that would look like this:

csharp Code:

private int GetRichTextBoxLineCount()
{
    return this.RichTextBox1.Lines.Length;
}

I'll let you implement the rest of the steps from there.

Thanks.

It's not working though.. When it reaches:

Code:

---

if (this.rtbOutput.InvokeRequired)

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The thread terminates, when I step though the code. The thread shouldn't terminate until all my code is done executing. When I click F5 to Run/Debug the program there is no sign that the thread is exiting...

can you give the full code you are using?
how do you know if the thread is being terminated?

Threads Merged At OP's Request

Here is the source code for my own version of the Console.ReadLine(). I ended up using threads anyway. I asked for these two 'forum threads' to be merged since the goal is the same.

I don't usually use System.Threading.Threads so I may be using it wrong.

Also while the thread (more specifically the loop) is running the UI is blocked, the user can't enter yes or no into the textbox.

Code:

---

  Thread threadConvo;
  string ReadLineResponse = "";
  public delegate string GetRtbOutputLineValueInvoker(int i);
  public delegate int GetRtbOutputLineLengthInvoker();
 
  private void txtInput_KeyUp(object sender, KeyEventArgs e)
        {
            if (e.KeyCode == Keys.Enter)
            {
                ProcessCommand(txtInput.Text);
            }
        }
        private void ProcessCommand(string cmd)
        {
            txtInput.Clear();
            Output(cmd, 1);
            switch (cmd)
            {
                case "exit":
                    Output("Exiting...", 0);
                    Application.Exit();
                    break;
                default:
                    //If..Then...Statements
                    if (cmd.StartsWith("delete"))
                    {
                        //How to Console.ReadLine()
                        threadConvo = new Thread(ReadLine);
                        threadConvo.IsBackground = true;
                        TimeSpan ts = new TimeSpan(0, 3, 0);
                        Output("Are you sure you would like to delete this file? (yes/no)", 0);
                        threadConvo.Start();
                        threadConvo.Join(ts);
                        if (ReadLineResponse == "yes")
                        {
                            Output(String.Format("Deleting {0}...", fi.FullName), 0);
                        }
                        else if (ReadLineResponse == "no")
                        {
                            Output("File deletion has been canceled.", 0);
                        }
                        else
                        {
                            Output("Invalid answer. 'No' has been presumed.", 0);
                            Output("File deletion has been canceled.", 0);
                        }
                    }
                    else
                    {
                        Output("The command '" + cmd.Trim() + "' is an unknown command.", 2);
                    }
                    break;
            }
        }
        public int GetRtbOutputLineLength()
        {
            if (this.rtbOutput.InvokeRequired)
            {
                return (int)this.rtbOutput.Invoke(new GetRtbOutputLineLengthInvoker(GetRtbOutputLineLength));
            }
            else
            {
                return this.rtbOutput.Lines.Length;
            }
        }
        public string GetRtbOutputLineValue(int i)
        {
            if (this.rtbOutput.InvokeRequired)
            {
                return (string)this.rtbOutput.Invoke(new GetRtbOutputLineValueInvoker(GetRtbOutputLineValue), i);
            }
            else
            {
                return this.rtbOutput.Lines[i].ToString();
            }
        }
        private void ReadLine()
        {
            int currLineIndex = GetRtbOutputLineLength();
            while (GetRtbOutputLineLength() < currLineIndex + 1)
            {
                if (GetRtbOutputLineLength() > currLineIndex)
                {
                    ReadLineResponse = GetRtbOutputLineValue(currLineIndex);
                    //threadConvo.Abort();
                }
            }
        }

---

Note * Output() appends text to rtbOutput.

still doesnt make sense why you are using threads here

Quote:

---

Originally Posted by Techno

still doesnt make sense why you are using threads here

---

What's the alternative?

Quote:

---

Originally Posted by Techno

a little hint: catch the event when the text changes. now, if the character is a carriage return, then read the previous line and use your switch block to determine what that line stated. or even better, use the keydown event args to determine what key was pressed.

---

oh... I'll rewrite the code and see what I get..

Here is revised (no threading) code:

Code:

---

        private void ProcessCommand(string cmd)
        {
            txtInput.Clear();
            Output(cmd, 1);
          if (rtbOutput.Lines.Length > 3)
            {
                if (rtbOutput.Lines[rtbOutput.Lines.Length - 3].Contains("?"))
                {
                    switch (rtbOutput.Lines[rtbOutput.Lines.Length - 3])
                    {
                        case "Response: Are you sure you would like to delete this file? (yes/no)":
                            if (cmd.Contains("yes"))
                            {
                                Output(String.Format("Deleting {0}...", fi.FullName), 0);
                            }
                            else
                            {
                                Output("File deletion has been canceled.", 0);
                            }
                            break;
                    }
                    return;
                }
            }
            switch (cmd)
            {
                case "time":
                    Output(DateTime.Now.ToString(), 0);
                    break;
                case "cls":
                    rtbOutput.Clear();
                    break;
                case "exit":
                    Output("Exiting...", 0);
                    Application.Exit();
                    break;
                default:
                    //If..Then...Statements
                    if (cmd.StartsWith("delete"))
                    {
                      Output("Are you sure you would like to delete this file? (yes/no)", 0);
                    }
                    else
                    {
                        Output("The command '" + cmd.Trim() + "' is an unknown command.", 2);
                    }
                    break;
            }
        }

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I guess the Threading was over doing it.. However it would of minimized the amount of code used. The above way requires me to write code for the question and code for the answer..

EDIT: Also 2 things I forgot to mention, Output outputs the string to rtbOutput attaching 'Response: ' or 'Command: ' to the beginning of the string. Also there is always a blank line at the end of the richtextbox.

EDIT: The imitating the Console.ReadLine may have been resolved but for the future and out of curiosity, why wasn't my thread working when I used the approach with the thread?