Want to win a PS4? Go Premium and enter to win our High-Tech Treats giveaway. Enter to Win

x
?
Solved

FindControl in Windows Form

Posted on 2004-09-27
10
Medium Priority
?
11,004 Views
Last Modified: 2010-08-02
Hi!

I have a Windows Form and I need to find a control in the form but I can't find out how to do it in a Windows Form!
I tried this:

((TextBox)this.FindControl(Form1.ActiveForm,"cn")).Text = "my text";

            private Control FindControl(Control Parent,string Target)
            {
                  Control FoundIt = null;
                  int i=0;
                  do
                  {
                        if(Parent.Controls[i].Name == Target)
                        {
                              FoundIt = Parent.Controls[i];
                        }
                        else
                        {
                              if(Parent.Controls[i].Controls.Count > 0)
                                    FoundIt = FindControl(Parent.Controls[i], Target);
                              i++;
                        }
                  }
                  while(FoundIt!=null || i>Parent.Controls.Count);
                  return FoundIt;
            }

But it don't work, it says tat the refrence of the object is not set to a instance of an object (or something like that)
0
Comment
Question by:aleborg
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 4
  • 2
  • 2
  • +2
10 Comments
 
LVL 48

Expert Comment

by:AlexFM
ID: 12158442
Can you describe what are you trying to do? I see that you use recursion, why? Recursive function must always have stop condition, and FindControl doesn't have it.
0
 
LVL 19

Accepted Solution

by:
Fahad Mukhtar earned 1000 total points
ID: 12158495
Control myControl = new Control ();
foreach (Control c in this.Controls)
if (c.Name == "textBox1")
      {
      myControl = c;                              
      MessageBox.Show(myControl .Name );
      }
0
 
LVL 9

Expert Comment

by:Thalox
ID: 12158684

I think your quit-condition is not right.

try this
while(FoundIt == null && i<Parent.Controls.Count);

to stop, if found, or no more controls...

this should work,

Thalox
0
Industry Leaders: We Want Your Opinion!

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

 
LVL 9

Expert Comment

by:Thalox
ID: 12158695
...
and I would use a while-loop, not do-while, because there could be controls, with no childs
0
 

Author Comment

by:aleborg
ID: 12158797
What I'm trying to do in this code is to find a textbox with a special name.
I have some "rows" in my form, each row has a drobpdownlist and some textbox, each control in a row is named txtArt1, txtText1, txtPris1
the number, 1 is the number of the row and txtArt is the DropdownList.
All dropdownlists are connected to private void txtArt1_SelectedIndexChanged(object sender, System.EventArgs e) on selectedindexchanged.

And txtArt1_SelectedIndexChanged looks like this:
            private void txtArt1_SelectedIndexChanged(object sender, System.EventArgs e)
            {
                  ComboBox dd = ((ComboBox)sender);
                  string cn = dd.Name.Replace("txtArt","");
                  
                  FakturaDLL.Products pr = new FakturaDLL.Products();
                  if(pr.GetProduct(dd.Text))
                  {
                        ((TextBox)this.FindControl(this.ParentForm,"txtText"+cn)).Text = pr.ProdText.ToString();
                        //txtPris1.Text = pr.ProdPrice.ToString(); - do the same thing with txtPris
                  }
                  else
                        MessageBox.Show("Produkten kunde inte hittas!");
            }

So what I'm trying to do is, that when txtArt is changed, the textboxes on the same row chould be updated.
0
 

Author Comment

by:aleborg
ID: 12159392
Tried this:
      ((TextBox)this.FindControl("txtText"+cn, this.Controls)).Text = pr.ProdText.ToString();

            private Control FindControl(string Target,Control.ControlCollection cont)
            {
                  Control myControl = new Control ();
                  foreach (Control c in cont)
                  {
                        if (c.Name == Target)
                        {
                              myControl = c;                        
                        }
                        else
                        {
                              if(c.Controls.Count >0)
                                    myControl=FindControl(Target,c.Controls);
                        }
                  }
                  return myControl;
            }

But it don't work, te reason that I wan't recursion is that all controls are placed in a tabcontrol so I need to check all controls and controls in the controls in the form.
If I have all controls in the form and not in a tabcontrol and use this private Control FindControl(string Target) and don't have recursion it works!
What am I doing wrong?
0
 
LVL 19

Expert Comment

by:Fahad Mukhtar
ID: 12166518

simply put the my code in a function which accepts a stting and returns a control.. call this function first time using:

FindControl(textBox2.Text, this);

and heres the FindControl
private void FindControl(string text, Control Parent)
{
                  
      Control myControl = new Control ();
      foreach(Control c in Parent.Controls)
      {
            if (c.Name == text)
            {
                  myControl = c;                              
                  MessageBox.Show(myControl.Name );
            }
            if (c.Controls.Count >0)
                  FindControl(text,c); // recursive call
                        
            }                  
}
0
 

Author Comment

by:aleborg
ID: 12167081
That's What I've done but it complains and says that the conversion isn't valid on this line:
((TextBox)this.FindControl("txtText"+cn, this)).Text = pr.ProdText.ToString();

My code:
            private void txtArt1_SelectedIndexChanged(object sender, System.EventArgs e)
            {
                  ComboBox dd = ((ComboBox)sender);
                  string cn = dd.Name.Replace("txtArt","");
                  
                  FakturaDLL.Products pr = new FakturaDLL.Products();
                  if(pr.GetProduct(dd.Text))
                  {
                        ((TextBox)FindControl("txtText"+cn, this)).Text = pr.ProdText.ToString();
                        ((TextBox)FindControl("txtPris"+cn, this)).Text = pr.ProdPrice.ToString();
                  }
                  else
                        MessageBox.Show("Produkten kunde inte hittas!");
            }
            
            private Control FindControl(string Target,Control Parent)
            {

                  Control myControl = new Control ();
                  foreach (Control c in Parent.Controls)
                  {
                        if (c.Name == Target)
                        {
                              myControl = c;
                        }
                        else
                        {
                              if(c.Controls.Count >0)
                                    myControl = FindControl(Target,c);
                        }
                  }
                  return myControl;    
            }
if i do this in FindControl:
if (c.Name == Target)
{
      myControl = c;
      MessageBox.Show(c.Name);
}
Then I can see that the right name is returned so nothing seems to be wrong with the function
0
 

Author Comment

by:aleborg
ID: 12167346
Solved it:
         private Control FindControl(string Target,Control Parent)
          {

               Control myControl = new Control ();
               foreach (Control c in Parent.Controls)
               {
                    if (c.Name == Target)
                    {
                         myControl = c;
                         break;
                    }
                    else
                    {
                         if(c.Controls.Count >0)
                              myControl = FindControl(Target,c);
                    }
               }
               return myControl;    
          }
0
 
LVL 12

Expert Comment

by:starlite551
ID: 33338701
private Control FindControl(string controlName,Control Parent)
{
               Control ct = new Control();
               bool flag = false;
               
               foreach(Control c in Parent.Controls)
               {
                         if(c.Name == controlName)
                         {
                                    ct = c;  
                                    falg = true;
                         }    
               }

               if(flag == true)
               {
                       retrun ct;
               }
               return null;  
}
0

Featured Post

Free Tool: Site Down Detector

Helpful to verify reports of your own downtime, or to double check a downed website you are trying to access.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Article by: Najam
Having new technologies does not mean they will completely replace old components.  Recently I had to create WCF that will be called by VB6 component.  Here I will describe what steps one should follow while doing so, please feel free to post any qu…
This article is for Object-Oriented Programming (OOP) beginners. An Interface contains declarations of events, indexers, methods and/or properties. Any class which implements the Interface should provide the concrete implementation for each Inter…
Sometimes it takes a new vantage point, apart from our everyday security practices, to truly see our Active Directory (AD) vulnerabilities. We get used to implementing the same techniques and checking the same areas for a breach. This pattern can re…
Please read the paragraph below before following the instructions in the video — there are important caveats in the paragraph that I did not mention in the video. If your PaperPort 12 or PaperPort 14 is failing to start, or crashing, or hanging, …

618 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question