C# Discussion Boards - CodeProject

5-Aug-09 2:05

Disclaimer: This separate yet related to a question I posted in the LINQ forum, but since its regarding a different issue (ListBox) it can't be considered cross posting.

I'm sure this is a simple issue, but I'm completely stumped.

Essentially, what I'm trying to do is have people move items between ListBoxes which are bound to Lists. One ListBox contains the items selected by the from the full list and the other contains the rest of the items from the full list, where originally, the second list box contained the full list (on the assumption that the user has not made any selections)

here's the code:

//Lists as properties
List<RCH.EL.EMR.Allergies> AllAllergies
{ get; set; }

List<RCH.EL.EMR.Allergies> RemainingAllergies
{ get; set; }

List<RCH.EL.EMR.Allergies> PatientAllergies
{ get; set; }

//Method that seperates the items in the lists
private void ResolveAllergies()
{
    RemainingAllergies = AllAllergies.Except(PatientAllergies).ToList();
}

//Method that binds
protected override void BindListBoxes()
{
    lstAllergies.DataSource = RemainingAllergies;
    lstAllergies.DisplayMember = "AllergyAr";
    lstAllergies.ValueMember = "ID";

    lstPatientAllergies.DataSource = PatientAllergies;
    lstPatientAllergies.DisplayMember = "AllergyAr";
    lstPatientAllergies.ValueMember = "ID";
}

//event handler methods that move the items from one list to the other (arrow buttons on the form)
private void btnAddLeft_Click(object sender, EventArgs e)
{
    
    PatientAllergies.Add((RCH.EL.EMR.Allergies)lstAllergies.SelectedItem);
    ResolveAllergies();
    lstAllergies.Refresh();
    lstPatientAllergies.Refresh();
    BindListBoxes();
}

private void btnAddRight_Click(object sender, EventArgs e)
{

    PatientAllergies.Remove((RCH.EL.EMR.Allergies)lstAllergies.SelectedItem);
    ResolveAllergies();
    lstAllergies.Refresh();
    lstPatientAllergies.Refresh();
    BindListBoxes();
}

As you can see, the Lists (not ListBoxes) are of the exact same type, so why the heck isn't the ListBox named lstPatientAllergies not binding properly? By that I mean that I can see that the lstPatientAllergies.DataSource has the proper number of elements and indeed the proper elements, but the lstPatientAllergies.Items is empty and always equals 0.

Ideas?

If the post was helpful, please vote, eh!

Current activities:
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Learning: Image analysis, LINQ

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Henry Minute5-Aug-09 5:04

5-Aug-09 5:04

Try this:

Add two BindingSource Components to your Form (remainderBindingSource and patientBindingSource, for my mods below)

//Method that binds
protected void BindListBoxes()
{
    this.remainderBindingSource.DataSource = RemainingAllergies;
    lstAllergies.DataSource = this.remainderBindingSource;
    //lstAllergies.DataSource = RemainingAllergies;
    lstAllergies.DisplayMember = "AllergyAr";
    lstAllergies.ValueMember = "ID";

    this.patientBindingSource.DataSource = PatientAllergies;
    lstPatientAllergies.DataSource = this.patientBindingSource;
    //lstPatientAllergies.DataSource = PatientAllergies;
    lstPatientAllergies.DisplayMember = "AllergyAr";
    lstPatientAllergies.ValueMember = "ID";
}

//event handler methods that move the items from one list to the other (arrow buttons on the form)
private void btnAddLeft_Click(object sender, EventArgs e)
{
    patientBindingSource.Add((RCH.EL.EMR.Allergies)lstAllergies.SelectedItem);
    //PatientAllergies.Add((RCH.EL.EMR.Allergies)lstAllergies.SelectedItem);
    remainderBindingSource.Remove((RCH.EL.EMR.Allergies)lstAllergies.SelectedItem);
    //ResolveAllergies();
    //lstAllergies.Refresh();
    //lstPatientAllergies.Refresh();
    //BindListBoxes();
}

I'm sure that a man of your calibre can work the rest out.

Hope this helps! Smile | :)

Henry Minute

Do not read medical books! You could die of a misprint. - Mark Twain
Girl: (staring) "Why do you need an icy cucumber?"
“I want to report a fraud. The government is lying to us all.”

Mustafa Ismail Mustafa5-Aug-09 5:19

5-Aug-09 5:19

Will do, but why the heck did this happen in the first place? I'm flabbergasted and befuddled.

Henry Minute5-Aug-09 5:35

5-Aug-09 5:35

Conceivably you could also do this by deriving your own collection class:
<pre>
      public class AllergyCollection : List<RCH.EL.EMR.Allergies>
      {
      }
</pre>

or better yet:
<pre>
      public class AllergyCollection : BindingList<RCH.EL.EMR.Allergies>
      {
      }
</pre>
and then implementing the <code>IRaiseItemChangedEvents</code> interface, but it's one heck of a lot of work, and <code>BindingSource</code> does it all already.

<blockquote class="FQ"><div class="FQA">Mustafa Ismail Mustafa wrote:</div>but why the heck did this happen in the first place</blockquote>

The problem is that the <code>DataSource</code> property of the <code>ListBox</code> is <b>probably</b> implemented like this:
<pre>
      public object DataSource
      {
            get
            {
                  return this.datasource;
            }

            set
            {
                  if (this.datasource != value)
                  {
                        this.datasource = value;
                        // now do loads of stuff that only happens if the datasource is a different object
                  }
            }
      }
</pre>

in your case, setting the <code>DataSource</code> to the same object (albeit modified) means the test fails and nothing is changed.

Mustafa Ismail Mustafa5-Aug-09 5:38

5-Aug-09 5:38

Henry Minute wrote:
and then implementing the IRaiseItemChangedEvents interface, but it's one heck of a lot of work, and BindingSource does it all already.

That's why I opted for the ready solution of the list box, before I encountered that snag.

Henry Minute wrote:
The problem is that the DataSource property of the ListBox is probably implemented like this:

I don't think so, the reason being I actually tried setting the DataSource to null and then resetting it the List<t> I had, and it still wouldn't work.

Henry Minute5-Aug-09 5:41

5-Aug-09 5:41

Mustafa Ismail Mustafa wrote:
I don't think so, the reason being I actually tried setting the DataSource to null and then resetting it the List I had, and it still wouldn't work.

Interesting!!
I'm wrong again. In that case I have no clue. Computers, hey. Laugh | :laugh:

Mustafa Ismail Mustafa5-Aug-09 5:47

5-Aug-09 5:47

Henry Minute wrote:
I'm wrong again.

Don't sweat it, I'm wrong more often than not Laugh | :laugh:

Henry Minute wrote:
Computers, hey. Laugh

Yep.

Sometimes, I wonder why I didn't listen to my mom and turned out a surgeon or carried on to study Organic Chemistry as a major!

Mustafa Ismail Mustafa5-Aug-09 5:35

5-Aug-09 5:35

Works like clock-work Smile | :)

Mucho thank you!

But WHY DID that strange occurrence happen?

Henry Minute5-Aug-09 5:38

Help in matching inputted string to a regex pattern

5-Aug-09 5:38

See my reply to your previous message, sorry about the formatting, I bollixed up the HTML Tags Checkboxes.

gamer11275-Aug-09 2:05

Re: Help in matching inputted string to a regex pattern

5-Aug-09 2:05

Can someone help me on how to match an entered string to a regex pattern?

I'm creating a program that would parse a for loop statement and check if the entered for loop statement is correct or not. So far I've been able to split that statement and pass it into an array. I then pass it again to a string variable after i put the splitted statement into that array. My only problem is how to check if the entered for loop statement is correct? I've been trying lots of pattern matching codes from the web but none of them have worked so far. The deadline will be next week but until now there hasn't been any progress.

My pattern isn't done yet too because i can't make a pattern that would match the >=, <= relational operators and the '--', '++' unary operators.

To make things easier, this is my code:

using System;
using System.Collections.Generic;
using System.Text;
using System.Text.RegularExpressions;
using System.Collections;

namespace MachineProblem
{
    class Program
    {

        static void Main(string[] args)
        {
        
            string passedStatement = " ";
            string[] stringHolder = null;

            GetStatement(stringHolder, ref passedStatement);
            SyntaxVerifier(stringHolder, ref passedStatement);

            Console.Read();

        }

        public static void GetStatement(string[] arrayBox, ref string statement)
        {

            Console.WriteLine("Write an example of a for loop statement: ");
            statement = Console.ReadLine();

            foreach (string token in Tokenizer(arrayBox, statement))
            {
                
            }

        }

        //the function that tokenizes the string
        public static string[] Tokenizer(string[] strBox, string tokenizeStatement)
        {

            strBox = null;

            //marks the end of the string to be tokenized
            Regex strTokenizer = new Regex(@"([\;\(\)\ \\])");

            for (int i = 0; i < strTokenizer.Split(tokenizeStatement).Length; i++)
            {

                //tokenized string passed to an empty array
                strBox = strTokenizer.Split(tokenizeStatement);

            }

            return strBox;

        }

        //the function used to check the entered statement if it's a correct syor not
        public static void SyntaxVerifier(string[] arrayString, ref string passedsyntax)
        {
            string pattern = @"(for\s*[\(]\s*int\s*[a-zA-Z\d]*\s*=\s*[\d]*\s*;\s*[a-zA-Z\d]*\s*[\<\>]\s*[\d]\s*;\s*[a-zA-z\d]*\s*[\-(1)])";
            string stringStatement = "for(int x=0; x<5; x++) Console.WriteLine(\"Hello\")";

            //arrayString = null;

            //arrayString = Tokenizer(arrayString, passedsyntax);


            foreach (string words in arrayString)
            {
                stringStatement = words;
                stringStatement.Trim();

            }
        }

    }
}

Thanks in Advance for those who could help Big Grin | :-D

musefan5-Aug-09 2:22

musefan

5-Aug-09 2:22

I have not tried to parse a for loop before but if I was to do it I would start by extracting the data between the for loops brackets (ensure you get the matching close bracket).

Then I would split it into three parts (using string.Split method with a semi-colon)

Then attempt to parse each part individually...

There also seems to be a number of things you may have overlooked such as; int is not the only valid datatype, the variable may be declared elsewhere thus meaning no datatype should be present, variable names can contain more than leters, there are more evaluation options than > and < etc...

Life goes very fast. Tomorrow, today is already yesterday.

Re: Help in matching inputted string to a regex pattern

gamer11275-Aug-09 2:31

Re: Help in matching inputted string to a regex pattern

5-Aug-09 2:31

I forgot to include that my parser program is created to parse just a simple for loop statement. it doesn't have to cover all of the possible examples of a for loop statement. We were instructed to only have one line statement after the for loop syntax meaning we don't have to include the open and close curly brackets.

example:

for(int abc989 = 10; abc989 >= 0; abc989--) Console.WriteLine("*");

for(int abc989 = 0; abc989 < 50; abc989++) Console.WriteLine("HelloWorld\n");

Those example are the only ones we can do at the moment since we're not in compiler design yet. We were given this kind of machine problem to apply one data structure which is a parse tree.

OriginalGriff5-Aug-09 2:54

OriginalGriff

5-Aug-09 2:54

gamer1127 wrote:
We were given this kind of machine problem to apply one data structure which is a parse tree.

Then why don't you use a parse tree, rather than try to force a regex to do the work?

forLoop
|--------------|--------------------------------------------------|
"for"          LoopConstruct                                      Statement
               |-------|------|-----|--------|------|------|
               "("     Init   ";"   EndCond  ";"    Step   ")"

etc.

No trees were harmed in the sending of this message; however, a significant number of electrons were slightly inconvenienced.

This message is made of fully recyclable Zeros and Ones

Re: Help in matching inputted string to a regex pattern

molesworth5-Aug-09 3:07

molesworth

5-Aug-09 3:07

I agree - RE's are really the wrong tool for this job, unless your lecturer/tutor is insisting you use them (although I'd be wondering why).

You say you're "not into compiler design yet" on your course, but I presume it's coming up eventually, and when it does you don't want to start off down the wrong road.

There are three kinds of people in the world - those who can count and those who can't...

Re: Help in matching inputted string to a regex pattern

gamer11275-Aug-09 4:00

Re: Help in matching inputted string to a regex pattern

5-Aug-09 4:00

Do you know any good source that i can read about parse tree?

riced5-Aug-09 4:22

riced

5-Aug-09 4:22

Google

Regards
David R
---------------------------------------------------------------
"Every program eventually becomes rococo, and then rubble." - Alan Perlis

Re: Help in matching inputted string to a regex pattern

gamer11275-Aug-09 4:39