Have Child, Got Parent, need Sibling

motocross1 · 02-10-2010, 04:51 PM

I use FindForm to get the Parent Object but the Object Members/Properties do not include access to the "public textBox1":

Code:

void button_click(System::Object^ sender, System::EventArgs^ e){
	Control^ ctrl = safe_cast<Control^>(sender);
	Form^ myForm = ctrl->FindForm();
	MessageBox::Show(myForm->Name,"The Name"); // works
	myForm->textBox1->Text = gcnew String("Hello"); // does not work
}

error C2039: 'textBox1' : is not a member of 'System::Windows::Forms::Form'

Yes, you can guess... I am trying to access it outside the class, which is why I do not simply use this->textBox1 - the call is made with:

this->Go->Click += gcnew System::EventHandler(button_click);

Any insights? Thanks.

_Mike · 02-10-2010, 05:04 PM

I haven't used managed c++ so I don't know how much it differs from C#, but in C# you could use

Code:

TextBox tb = (TextBox)myForm.Controls["textBox1"];

brewbuck · 02-10-2010, 05:19 PM

Quote:

Originally Posted by motocross1

Code:

Form^ myForm = ctrl->FindForm();

Instead of Form, you should be using whatever class your main form actually is. Form is just a base class, it has no such members...

motocross1 · 02-10-2010, 07:48 PM

Quote:

TextBox tb = (TextBox)myForm.Controls["textBox1"];

I not very good at converting C# to C++ I get an error with:
TextBox tb = safe_cast<TextBox^>(myForm->Controls["textBox1"]);
'System::Windows::Forms::TextBox' : class does not have a copy-constructor

Quote:

Instead of Form, you should be using whatever class your main form actually is.

I have tried directly accessing FormNamespace::Form1::textBox1 to no avail... can you give me an example of what you mean otherwise. And by the way, myForm->Name does give 'Form1'.

motocross1 · 02-10-2010, 07:55 PM

Actually I added a carat and it complied without errors:
TextBox^ tb = safe_cast<TextBox^>(myForm->Controls["textBox1"]);

But then crashed when I clicked the button with:
Object reference not set to an instance of an object.

_Mike · 02-10-2010, 08:22 PM

Quote:

I have tried directly accessing FormNamespace::Form1::textBox1 to no avail... can you give me an example of what you mean otherwise. And by the way, myForm->Name does give 'Form1'.

What brewbuck is saying is that instead of
Form^ myForm
you should use the class that is derived from Form.
By the sound of things I'm guessing you should use
Form1^ myForm = ctrl->FindForm();
or if FindForm() is a member function of Form1 I think you can just cast 'sender' to Form1 directly
Form1^ myForm = safe_cast<Form1^>(sender);

Quote:

Actually I added a carat and it complied without errors:
TextBox^ tb = safe_cast<TextBox^>(myForm->Controls["textBox1"]);

But then crashed when I clicked the button with:
Object reference not set to an instance of an object.

Are you checking that tb isn't NULL before trying to dereference it?

motocross1 · 02-11-2010, 01:19 PM

Tried this: ---------------------------------------------Pure-FYI-OK-to-Skip-It---------
Form1^ myForm = safe_cast<Form1^>(sender);

It complies, then crashes when button is clicked:
Unable to cast object of type 'System.Windows.Forms.Button' to type 'FormNamespace.Form1'

In case you didn't know... FindForm() is a .NET function: Control.FindForm Method (System.Windows.Forms)
I'm OK with using it to hook the parent form.

As for:-------------------------------------------------Please-Dont-Skip-This---------

Code:

TextBox^ tb = safe_cast<TextBox^>(myForm->Controls["textBox1"]);
if(!tb){ MessageBox::Show("Not tb","Alert"); return; } // I added this

Yep, when I click the button it says "Not tb"... but, since I have textBox1 inside splitContainer1, I tried:

Code:

SplitContainer^ sc = safe_cast<SplitContainer^>(myForm->Controls["splitContainer1"]);
sc->SplitterDistance=200; // IT WORKS - YEAH!

So, how can I hook textBox1 - I tried and failed with:

Code:

TextBox^ tb = safe_cast<TextBox^>(sc->Controls["textBox1"]);
TextBox^ tb = safe_cast<TextBox^>(myForm->Controls["splitContainer1->textBox1"]);
TextBox^ tb = safe_cast<TextBox^>(myForm->Controls["splitContainer1::textBox1"]);

Ideas?

brewbuck · 02-11-2010, 02:08 PM

What I meant was this...

Code:

Form1^ myForm = safe_cast<Form1^>( ctrl->FindForm() );

_Mike · 02-11-2010, 02:15 PM

Quote:

Originally Posted by motocross1

In case you didn't know... FindForm() is a .NET function: Control.FindForm Method (System.Windows.Forms)
I'm OK with using it to hook the parent form.

Ah I see, thanks. I had never heard of it before so I thought it was a function you had written yourself

Quote:

Ideas?

You should have mentioned that the textbox was in a splitcontainer

Code:

System::Void button1_Click(System::Object^  sender, System::EventArgs^  e)
{
	Control^ ctrl = safe_cast<Control^>(sender);
	Form1^ myForm = safe_cast<Form1^>(ctrl->FindForm());
	TextBox^ tb = safe_cast<TextBox^>(myForm->splitContainer1->Panel2->Controls["textBox1"]);
	tb->Text = "It works!";
}

I'm using a form layout of:

Code:

Form1
  splitContainer1
    panel1
      button1
    panel2
      textbox1

Adjust variable names to fit your project.

motocross1 · 02-11-2010, 03:06 PM

Awesome!!

Thanks Everyone

And, in case anyone is curious... Yes it is possible to take your Form functions out of the form.h and put them into a source.cpp --if you are using VC++ 2008 Express the final trick is to attach the events in the Form1_Load so that the designer doesn't grip about a parse error:

Code:

private: System::Void Form1_Load(System::Object^ sender, System::EventArgs^ e){
		this->button->Click += gcnew System::EventHandler(button_click); // without "this," hence the VC++ grip
}

Then just move the event functions to where ever.

02-10-2010, 04:51 PM	#1
motocross1 Registered User Join Date: Feb 2010 Posts: 7	Have Child, Got Parent, need Sibling I use FindForm to get the Parent Object but the Object Members/Properties do not include access to the "public textBox1": Code: void button_click(System::Object^ sender, System::EventArgs^ e){ Control^ ctrl = safe_cast<Control^>(sender); Form^ myForm = ctrl->FindForm(); MessageBox::Show(myForm->Name,"The Name"); // works myForm->textBox1->Text = gcnew String("Hello"); // does not work } error C2039: 'textBox1' : is not a member of 'System::Windows::Forms::Form' Yes, you can guess... I am trying to access it outside the class, which is why I do not simply use this->textBox1 - the call is made with: this->Go->Click += gcnew System::EventHandler(button_click); Any insights? Thanks.
motocross1 is offline

02-10-2010, 05:04 PM	#2
_Mike Registered User Join Date: Jan 2010 Posts: 238	I haven't used managed c++ so I don't know how much it differs from C#, but in C# you could use Code: TextBox tb = (TextBox)myForm.Controls["textBox1"];
_Mike is offline

02-10-2010, 07:55 PM	#5
motocross1 Registered User Join Date: Feb 2010 Posts: 7	Actually I added a carat and it complied without errors: TextBox^ tb = safe_cast<TextBox^>(myForm->Controls["textBox1"]); But then crashed when I clicked the button with: Object reference not set to an instance of an object.
motocross1 is offline

02-11-2010, 01:19 PM	#7
motocross1 Registered User Join Date: Feb 2010 Posts: 7	Tried this: ---------------------------------------------Pure-FYI-OK-to-Skip-It--------- Form1^ myForm = safe_cast<Form1^>(sender); It complies, then crashes when button is clicked: Unable to cast object of type 'System.Windows.Forms.Button' to type 'FormNamespace.Form1' In case you didn't know... FindForm() is a .NET function: Control.FindForm Method (System.Windows.Forms) I'm OK with using it to hook the parent form. As for:-------------------------------------------------Please-Dont-Skip-This--------- Code: TextBox^ tb = safe_cast<TextBox^>(myForm->Controls["textBox1"]); if(!tb){ MessageBox::Show("Not tb","Alert"); return; } // I added this Yep, when I click the button it says "Not tb"... but, since I have textBox1 inside splitContainer1, I tried: Code: SplitContainer^ sc = safe_cast<SplitContainer^>(myForm->Controls["splitContainer1"]); sc->SplitterDistance=200; // IT WORKS - YEAH! So, how can I hook textBox1 - I tried and failed with: Code: TextBox^ tb = safe_cast<TextBox^>(sc->Controls["textBox1"]); TextBox^ tb = safe_cast<TextBox^>(myForm->Controls["splitContainer1->textBox1"]); TextBox^ tb = safe_cast<TextBox^>(myForm->Controls["splitContainer1::textBox1"]); Ideas?
motocross1 is offline

02-11-2010, 02:08 PM	#8
brewbuck Staff software engineer Join Date: Mar 2007 Location: Portland, OR Posts: 6,014	What I meant was this... Code: Form1^ myForm = safe_cast<Form1^>( ctrl->FindForm() ); __________________ "Congratulations on your purchase. To begin using your quantum computer, set the power switch to both off and on simultaneously." -- raftpeople@slashdot
brewbuck is offline

02-11-2010, 03:06 PM	#10
motocross1 Registered User Join Date: Feb 2010 Posts: 7	Awesome!! Thanks Everyone And, in case anyone is curious... Yes it is possible to take your Form functions out of the form.h and put them into a source.cpp --if you are using VC++ 2008 Express the final trick is to attach the events in the Form1_Load so that the designer doesn't grip about a parse error: Code: private: System::Void Form1_Load(System::Object^ sender, System::EventArgs^ e){ this->button->Click += gcnew System::EventHandler(button_click); // without "this," hence the VC++ grip } Then just move the event functions to where ever.
motocross1 is offline

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