Windows forms application

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i am having a problem creating a variable to check whether a button is still on a form or if it has been removed in order to open another form....please help.
here is the code snippet for the button:

C#

private void button6_Click(object sender, EventArgs e)
        {
            button6.Text = "4";
            if (t == "")
            {
                t = button6.Text;
            }
            else
            {
                if (w == "")
                {
                    w = button6.Text;
                    if (w == t)
                    {
                        this.Controls.Remove(button7);
                        this.Controls.Remove(button6);
                    }
                    else
                    {
                        foreach (Control ctrl in this.Controls)
                        {
                            if (ctrl is Button)
                            {
                                ctrl.ResetText();
                            }
                        }
                    }
                }
                else
                {
                    w = "";
                    t = "";
                    t = button6.Text;
                }
            }
        }

Posted 5-Sep-11 10:28am

lethabo11

Updated 5-Sep-11 10:42am

Wendelius

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Comments

Philippe Mori 5-Sep-11 20:06pm

Humm... Removing button is probably not considered a good UI design... Why would remove buttons before opening another form. It is preferable to disable buttons that should not be used in most scenarios.

Sergey Alexandrovich Kryukov 5-Sep-11 21:16pm

I think your advice is the only reasonable one so far... I would up-vote it.
--SA

3 solutions

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GParkings · Accepted Answer · 2011-09-05T11:10:00

if the button is a direct child of the form:

C#

bool isButtonOnForm = this.Controls.Contains(button6);

otherwise you will need a recursive method:

C#

public bool IsButtonFound(Control ctl, Button btn)
{
    if (!ctl.HasChildren){return false;}

    foreach (Control child in ctl.Controls)
    {
        if (child == btn){ return true;}
        if (IsButtonFound(child, btn)){ return true;}
    }

    return false;
}

this looks walks the control hierarchy until it finds the button (at which point all recursive calls return true all the way up to the root call) or until it runs out of controls

Wendelius · Accepted Answer · 2011-09-05T11:03:00

Solution 1

So do you want to know if a control exists on your form based on it's name? If that is the case I think one easy way is to use ContainsKey method. Something like:

C#

If (this.Controls.ContainsKey("button6") {
...

Posted 5-Sep-11 11:03am

Wendelius

Comments

GParkings 5-Sep-11 17:23pm

haha, you beat me to that one :) have 5

Wendelius 5-Sep-11 17:27pm

Thanks :)

lethabo11 5-Sep-11 18:14pm

Thanks Mika. Does the containsKey method only check the button's presence? How about when the button is not there?

lethabo11 5-Sep-11 17:47pm

Thanks Mika. Does the containsKey method only check the button's presence? How about when the button is not there?

Wendelius 5-Sep-11 17:59pm

Not sure what you mean with presence. If the button is removed from the forms controls collection, ContainsKey isn't finding it anymore.

lethabo11 5-Sep-11 18:18pm

I want to open another form when the button6 control is no longer on the form...so is there a condition i can use to confirm that the control has been removed from the form...I am a beginner to windows forms Applications.

Wendelius 5-Sep-11 18:28pm

You can also do this vice versa. Check what is the parent property value for button6. If it's null, it doesn't have a parent anymore.

lethabo11 6-Sep-11 0:18am

Thank you for your help

Wendelius 6-Sep-11 0:19am

You're welcome :)

Sander Rossel · Accepted Answer · 2011-09-05T11:14:00

Solution 3

Mika's answer seems perfectly fine. Here is an alternative though.
At the time of the removal of your button you could set a boolean field.
Later you would only need to check if it is true or false.

C#

private bool _btn6Removed;

private void Click(object sender, EventArgs e){
   this.Controls.Remove(button6);
   _btn6Removed = true;
}
//...
if (_btn6Removed){
//...
}

Posted 5-Sep-11 11:14am

Sander Rossel

Comments

lethabo11 5-Sep-11 18:00pm

Thank you

lethabo11 5-Sep-11 18:31pm

your method is working fine but the problem is that i have 16 buttons that i have to remove from the form before i can set my condition which in this case will be opening another form...how do i go about it? i tried using the boolean field for each button but its not working.

Sander Rossel 5-Sep-11 18:37pm

I guess the best approach is to simply delete all buttons, then set the boolean and check it.
this.Control.Remove(button1);
this.Control.Remove(button2);
this.Control.Remove(button3);
this.Control.Remove(button4);
...
_btnsRemoved = true;

if (_btnsRemoved){
//code
}

You could also use recursion to remove all Buttons in one Method, look at solution 2 for an example.
Solution 1 should also still work.
I think you'll get it working, good luck! :)

lethabo11 6-Sep-11 0:16am

I can not remove the all buttons at the same as they are removed in pairs when they contain the same text. Two buttons have to be matched before they can be removed. Thanks a loy for your help, I will keep on trying...am a programming beginner.

lethabo11 6-Sep-11 0:10am

how do i use your method for many buttons on the same form? i have 16 buttons that i have to remove.

Sander Rossel 6-Sep-11 2:01am

Something like
this.Control.Remove(button1);
this.Control.Remove(button2);
_btn1And2Removed = true;

this.Control.Remove(button3);
this.Control.Remove(button4);
_btn3And4Removed = true;
...

if (_btn1And2Removed && _btn3And4Removed){
//code
}

Maybe?

Windows forms application

3 solutions

Solution 2

Solution 1

Solution 3

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