[SOLVED] C++ sender

[plutomed]

I have a function for a press of a button on a form.

 

private: System::Void GridControl(System::Object^ sender, System::EventArgs^ e) {

			  //String^ Details = sender->ToString()->Substring(34);

			  Control ctrl = (Control)sender;
			  
			  MessageBox::Show(ctrl.Name, "",MessageBoxButtons::OK);
		  }

 

When I try to compile the program it wont let me. I get the error:

 

error C2440: 'type cast' : cannot convert from 'System::Object ^' to 'System::Windows::Forms::Control'

 

All I'm trying to do is get the name of the button that called the function.

 

I found this way of doing it on several places on Google, I dunno if it is correct or not but my compiler doesn't like it.

[Bendude14]

why cast it to a control? can you not just use sender.Name?

[plutomed]

No. When I try sender.Name I get the error C2228 Left of '.Name' must have a class/struct/union.

Also When I try sender->Name I get error C2039 Name is not a member of System::Object

 

When I echo out what sender is: sender->ToString(); I get: System.Windows.Forms.Button, Text:<Text of button>

[KevinM1]

Have you tried casting it as a button?  Like:

Button ctrl = (Button)sender;

 

I do that in C#, and it works fine.

[plutomed]

I think its just VS2008 being an arse!

 

Tried it like that and still didn't work.

 

error C2440: 'type cast' : cannot convert from 'System::Object ^' to 'System::Windows::Forms::Button'

[KevinM1]

I think its just VS2008 being an arse!

 

Tried it like that and still didn't work.

 

error C2440: 'type cast' : cannot convert from 'System::Object ^' to 'System::Windows::Forms::Button'

 

Hmm...what does the '^' denote?  I'm not familiar with that marker/operator.

[plutomed]

I don't really know...

 

But if I don't have it there I get the error:

 

error C3352: 'void Battleshipssssssss::Form1::GridControl(System::Object,System::EventArgs ^)' : the specified function does not match the delegate type 'void (System::Object ^,System::EventArgs ^)'

 

Also I have always used "element.property", now I'm having to use "element->property". Do you know the difference?

[KevinM1]

I don't really know...

 

But if I don't have it there I get the error:

 

error C3352: 'void Battleshipssssssss::Form1::GridControl(System::Object,System::EventArgs ^)' : the specified function does not match the delegate type 'void (System::Object ^,System::EventArgs ^)'

 

Also I have always used "element.property", now I'm having to use "element->property". Do you know the difference?

 

Well, for the first problem, I'd try keeping the method signature the same as what it was, but cast the sender as a Button^ (whatever that's supposed to mean).  The worst that can happen is another compiler error.

 

For the second, the -> operator is used to dereference a pointer.  The element variable is a pointer of some type, and you're dereferencing it to get a hold of its property.

 

I wonder if the '^' is a Microsoft/.NET/Visual Studio thing to represent a pointer.  Usually it's denoted by a '*', like say int* num, but the other operator looks to be used in a similar fashion here.

[KevinM1]

Hey, I found this article which may help: http://msdn.microsoft.com/en-us/library/yk97tc08.aspx

[Ninjakreborn]

If that doesn't work, try CodeBlocks and Ming.  That seems to be a good combination for me. I used VS2008 for awhile but it just wasn't working for me due to various reasons.

[plutomed]

Hey, I found this article which may help: http://msdn.microsoft.com/en-us/library/yk97tc08.aspx

 

If the syntax worked the way it was, why change it. :/ And I tried changing it to a button^ and it said that is wasn't in the right format for System::Void.

[KevinM1]

With more digging, I believe I've found the solution:

 

Button^ ctrl = safe_cast<Button^>(sender);

[plutomed]

Yeaaaaaa

 

Thanks so much

[plutomed]

Ok, I'm having another little problem...

 

I'm getting the error c2065 GameBoardP2 undeclared identifier. It blatently is identified as when I hover over that line in the code it pops up saying char GameBoardP2[9][9].

 

GameBoardP2 is declared in a header file.

 

Could you give me any ideas 

[KevinM1]

Ok, I'm having another little problem...

 

I'm getting the error c2065 GameBoardP2 undeclared identifier. It blatently is identified as when I hover over that line in the code it pops up saying char GameBoardP2[9][9].

 

GameBoardP2 is declared in a header file.

 

Could you give me any ideas 

 

To be honest, I'm not sure.  My C++ is very rusty.  Are you certain you've included the header file?

[plutomed]

Ok, I re-compiled it and it worked.

 

I'm now having a problem converting from a string to a int.

 

I'm not having a good day lol.

 

C2664: 'std::basic_istringstream<_Elem,_Traits,_Alloc>::basic_istringstream(std::ios_base::openmode)' : cannot convert parameter 1 from 'System::String ^' to 'std::ios_base::openmode'

[KevinM1]

It looks like you may be dealing with another stack handle thingie.  Are you trying to convert from string to int, or string^ to int?

[plutomed]

Yea...Its a string^ (string pointer I think).

 

 

[KevinM1]

Yea...Its a string^ (string pointer I think).

 

It's sort of a pointer.  It's a handle to an object (this time, a string) on the managed (read: .NET) heap.  Try using the same safe_cast thing I showed you before to turn it into an int^.

[plutomed]

I tried that and nope, didn't want to do it.

 

Can you tell me what an l-value is?

 

Gawd I have a lot to learn lol. All languages are so different.

 

*edit*

 

Is it a Left hand side value?

[plutomed]

I just thought you basically don't know what I'm trying to do.

 

I have a form with a load of buttons. When I click one I want it to update an array at the point of the name of the button. Each button has the name eg.12.

 

The array looks like this:

 

char GameBoardP1[9][9] = {

{0,0,0,0,0,0,0,0,0},

{0,0,0,0,0,0,0,0,0},

{0,0,0,0,0,0,0,0,0},

{0,0,0,0,0,0,0,0,0},

{0,0,0,0,0,0,0,0,0},

{0,0,0,0,0,0,0,0,0},

{0,0,0,0,0,0,0,0,0},

{0,0,0,0,0,0,0,0,0},

{0,0,0,0,0,0,0,0,0}

};

 

So if I press the button named 12, I want it to go to the array at GameBoardP1[1][2].

 

The way I have doe it so far is:

private: System::Void GridControl(System::Object^ sender, System::EventArgs^ e) {

			  Button^ ctrl = safe_cast<Button^>(sender);
			  String^ Details = ctrl->Name->ToString();

			  MessageBox::Show(Details[2],"",MessageBoxButtons::OK); //I'm trying to get Details[2] to a const char*

			  /*
			  switch(GameBoardP2[strtol(Details[2], NULL, 10)][strtol(Details[3], NULL, 10)])
			  {
			  case 66:
				  MessageBox::Show("Hit", "Response:", MessageBoxButtons::OK);
				  ctrl->Text = "Hit";
				  lblInfo->AppendText("Player 1 just hit a ship.\n");
				  lblInfo->ScrollToCaret();
				  break;

			  default:
				  MessageBox::Show("Miss", "Response:", MessageBoxButtons::OK);
				  ctrl->Text = "Miss";
				  lblInfo->AppendText("Player 1 just missed.\n");
				  lblInfo->ScrollToCaret();
				  break;
			  }
			  */

			  ctrl->Enabled = false;
		  }		  }

[KevinM1]

I tried that and nope, didn't want to do it.

 

Can you tell me what an l-value is?

 

Gawd I have a lot to learn lol. All languages are so different.

 

*edit*

 

Is it a Left hand side value?

 

Yup, an l-value is a left hand value.  It generally means that it's something that can be assigned to, but not always (const variables are considered l-values).  l-values can be used as r-values, but not vice versa.

 

More info: http://publib.boulder.ibm.com/infocenter/macxhelp/v6v81/index.jsp?topic=/com.ibm.vacpp6m.doc/language/ref/clrc05lvalue.htm

[plutomed]

Thanx so much for all your help.