Re: c problem - Managed C++/CLI Discussion Boards

Hamid_RT19-Feb-07 19:00

19-Feb-07 19:00

Is better you ask about your problem not I need to a code.You can starting to write it and if you have problem then ask about your problem Wink | ;)

WhiteSky

Re: need code

Christian Graus21-Feb-07 11:31

Christian Graus

21-Feb-07 11:31

You have several issues.

1 - this is the C++/CLI forum. If there's a place for C questions, it, by definition, is not here
2 - this sounds like a reasonably complex task. One has to ask how you got this far in your course, if you can't read.
3 - We're not here to do your homework, and if we did do it, you wouldn't be learning, now would you ?

Christian Graus - Microsoft MVP - C++
Metal Musings - Rex and my new metal blog
"I am working on a project that will convert a FORTRAN code to corresponding C++ code.I am not aware of FORTRAN syntax" ( spotted in the C++/CLI forum )

c problem

p_18-Feb-07 18:25

18-Feb-07 18:25

please tell me that
can we define a function outside the main() in c language
please give an example
thanks

Re: c problem

prasad_som18-Feb-07 18:49

prasad_som

18-Feb-07 18:49

paras_s12 wrote:
can we define a function outside the main()

And how it can be defined inside main ?

This question is out side scope of this forum. Rather ask in VC++[^] forum.

Prasad
Notifier using ATL | Operator new[],delete[][^]

Re: c problem

Mark Salsbery19-Feb-07 9:01

Mark Salsbery

19-Feb-07 9:01

prasad_som wrote:
This question is out side scope of this forum. Rather ask in VC++[^] forum.

It's outside the scope of that forum too Poke tongue | ;-P

Great job, team. Head back to base for debriefing and cocktails.

Re: c problem

p_18-Feb-07 19:12

18-Feb-07 19:12

can anybody tell me abt this

Re: c problem

prasad_som18-Feb-07 19:16

prasad_som

18-Feb-07 19:16

Would you mind posting it in correct forum ?

Prasad
Notifier using ATL | Operator new[],delete[][^]

Re: c problem

p_18-Feb-07 19:20

18-Feb-07 19:20

please sir tell me in which forum i will put this one

Re: c problem

bsaksida18-Feb-07 20:59

bsaksida

18-Feb-07 20:59

This forum is for Managed c++/cli

Your c question must be in Visual C++ forum here on CP.

Re: c problem

Hamid_RT19-Feb-07 19:01

Hamid_RT

19-Feb-07 19:01

Visual C++ / MFC[^]

WhiteSky

Re: c problem

toxcct20-Feb-07 5:22

toxcct

20-Feb-07 5:22

shut your big mouth and open your ears Sleepy | :zzz:

[VisualCalc][Flags Beginner's Guide] | [Forums Guidelines][My Best Advice]

Re: c problem

Newbie0019-Feb-07 5:11

Newbie00

19-Feb-07 5:11

I've better question:

Can we define a function inside the main() in c language?
buahaha

Re: c problem

ThatsAlok21-Feb-07 6:19

ThatsAlok

21-Feb-07 6:19

paras_s12 wrote:
can we define a function outside the main() in c language

you ar eon wrong forum dude... try http://www.codeproject.com/script/comments/forums.asp?forumid=1647

"Opinions are neither right nor wrong. I cannot change your opinion. I can, however, change what influences your opinion." - David Crow

cheers,
Alok Gupta
VC Forum Q&A :- I/ IV
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Error with 'System.NullReferenceException' [modified]

thesad17-Feb-07 4:12

thesad

17-Feb-07 4:12

I had written :

for(int i=0; i <10; i++){<br />
  em[i]->pct = (gcnew System::Windows::Forms::PictureBox());<br />
  em[i]->pct->Location = System::Drawing::Point(250, 250);<br />
  em[i]->pct->Visible = true;<br />
  em[i]->pct->Size = System::Drawing::Size(50, 50);<br />
}

And I got this error :

An unhandled exception of type 'System.NullReferenceException' occurred in Little tanks.exe

Additional information: Object reference not set to an instance of an object.

at this line : em[i]->pct = (gcnew System::Windows::Forms::PictureBox());

what did I do wrong?

Re: Error with 'System.NullReferenceException'

Newbie0017-Feb-07 10:07

Newbie00

17-Feb-07 10:07

How have you defined the em array?

Re: Error with 'System.NullReferenceException'

Christian Graus17-Feb-07 10:08

Christian Graus

17-Feb-07 10:08

em[i] is null, you probably created an array and didn't create the objects in it

Re: Error with 'System.NullReferenceException'

thesad17-Feb-07 12:16

thesad

17-Feb-07 12:16

the em array defined so : static array<tank^>^ em;
and tank is structure :

ref struct tank {<br />
 int step_x, step_y;  <br />
 System::Windows::Forms::PictureBox^ pct;<br />
};

What do you mean saying to create objects for array? Smile | :)

Re: Error with 'System.NullReferenceException'

prasad_som17-Feb-07 15:44

prasad_som

17-Feb-07 15:44

thesad wrote:
static array^ em;

You have not initialized array here.
Array can be initialized as given in MSDN example.

array<MyClass ^> ^ MyArray = gcnew array<MyClass ^>(100);

Prasad
Notifier using ATL | Operator new[],delete[][^]

Re: Error with 'System.NullReferenceException'

thesad17-Feb-07 21:44

thesad

17-Feb-07 21:44

I wrote taht you had sad, but still at same line is that error

Re: Error with 'System.NullReferenceException'

prasad_som18-Feb-07 1:22

prasad_som

18-Feb-07 1:22

Would interesting to see, how you have done that. There are two possiblitites,
1. You have not allocated memory for it.
2. You are accessing invalid index.

Prasad
Notifier using ATL | Operator new[],delete[][^]

Re: Error with 'System.NullReferenceException'

thesad18-Feb-07 2:05

thesad

18-Feb-07 2:05

Here is all code :

<br />
#pragma once<br />
namespace Littletanks {<br />
ref struct tank {<br />
  int step_x, step_y;  <br />
  System::Windows::Forms::PictureBox^ pct;<br />
};<br />
using namespace System;<br />
using namespace System::ComponentModel;<br />
using namespace System::Collections;<br />
using namespace System::Windows::Forms;<br />
using namespace System::Data;<br />
using namespace System::Drawing;<br />
public ref class wnd_main : public System::Windows::Forms::Form {<br />
	public: wnd_main(void) {<br />
			InitializeComponent();<br />
		    }<br />
	protected: ~wnd_main() {<br />
			if (components) delete components;<br />
		    }<br />
	private: System::ComponentModel::IContainer^  components;<br />
    private: int max_x, max_y, min_x, min_y;<br />
    private: tank usr, b_usr;<br />
    private: static array<tank^>^ em; <br />
    private: static array<tank^>^ b_em; <br />
	<br />
#pragma region Windows Form Designer generated code<br />
		void InitializeComponent(void)<br />
		{<br />
			this->components = (gcnew System::ComponentModel::Container());<br />
			this->usr.pct = (gcnew System::Windows::Forms::PictureBox());<br />
			this->b_usr.pct = (gcnew System::Windows::Forms::PictureBox());<br />
			this->SuspendLayout();<br />
			// <br />
			// pct_usr<br />
			// <br />
			this->usr.pct->Location = System::Drawing::Point(235, 391);<br />
			this->usr.pct->Size = System::Drawing::Size(50, 50);<br />
			this->usr.pct->TabStop = false;<br />
			// <br />
			// pct_em<br />
			//<br />
			array<tank^>^ em = gcnew array<tank^>(10);<br />
			array<tank^>^ b_em = gcnew array<tank^>(10);<br />
			for(int i=0; i <10; i++){<br />
			  this->em[i]->pct = gcnew System::Windows::Forms::PictureBox();<br />
			  this->em[i]->pct->Location = System::Drawing::Point(250, 250);<br />
			  this->em[i]->pct->Visible = true;<br />
			  this->em[i]->pct->Size = System::Drawing::Size(50, 50);<br />
              this->b_em[i]->pct = gcnew System::Windows::Forms::PictureBox();<br />
			  this->b_em[i]->pct->Load("b_em[i]->jpg");<br />
		      this->b_em[i]->pct->Location = System::Drawing::Point(13, 64);<br />
			  this->b_em[i]->pct->Size = System::Drawing::Size(5, 5);<br />
			  this->b_em[i]->pct->Visible = false;<br />
			  this->Controls->Add(this->b_em[i]->pct);<br />
			  this->Controls->Add(this->em[i]->pct);<br />
			} <br />
			this->b_usr.pct->Load("b_usr.jpg");<br />
			this->b_usr.pct->Location = System::Drawing::Point(97, 142);<br />
			this->b_usr.pct->Size = System::Drawing::Size(5, 5);<br />
			this->b_usr.pct->Visible = false;<br />
			// wnd_main<br />
			// <br />
			this->AutoScaleDimensions = System::Drawing::SizeF(6, 13);<br />
			this->AutoScaleMode = System::Windows::Forms::AutoScaleMode::Font;<br />
			this->BackColor = System::Drawing::SystemColors::Window;<br />
			this->ClientSize = System::Drawing::Size(500, 500);<br />
			this->MaximizeBox = false;<br />
			this->MinimizeBox = false;<br />
			this->Controls->Add(this->b_usr.pct);<br />
			this->Controls->Add(this->usr.pct);<br />
			this->KeyDown += gcnew System::Windows::Forms::KeyEventHandler(this, &wnd_main::wnd_main_KeyDown);<br />
			this->Name = L"wnd_main";<br />
			this->Text = L"Little tanks ";<br />
			this->statusStrip1->ResumeLayout(false);<br />
			this->statusStrip1->PerformLayout();<br />
			this->menuStrip1->ResumeLayout(false);<br />
			this->menuStrip1->PerformLayout();<br />
			this->ResumeLayout(false);<br />
			this->PerformLayout();<br />
		}<br />
#pragma endregion<br />

Re: Error with 'System.NullReferenceException'

prasad_som18-Feb-07 4:20

prasad_som

18-Feb-07 4:20

Here, you had made couple of mistakes,

thesad wrote:
array^ em = gcnew array(10);
array^ b_em = gcnew array(10);

Here, again you are defining local variables. It should be like this,

this->em = gcnew array<tank^>(10);
this->b_em = gcnew array<tank^>(10);

Again, simply defining array doesn't initializes its members, you need to allocate tank variable for each index. So, your code can be modified like this,

thesad wrote:
for(int i=0; i <10; i++){
this->em[i]->pct = gcnew System::Windows::Forms::PictureBox();
this->em[i]->pct->Location = System::Drawing::Point(250, 250);

Modify this to,

for(int i=0; i <10; i++){
em[i] = gcnew tank;//create tank object for each index
this->em[i]->pct = gcnew System::Windows::Forms::PictureBox();
this->em[i]->pct->Location = System::Drawing::Point(250, 250);
//your code follows

Prasad
Notifier using ATL | Operator new[],delete[][^]

Re: Error with 'System.NullReferenceException' [modified]

thesad18-Feb-07 4:48

thesad

18-Feb-07 4:48

thank you for your help Smile | :)

Re: Error with 'System.NullReferenceException'

Christian Graus18-Feb-07 9:11

Christian Graus

18-Feb-07 9:11

If you create a new Array, of 100 tank objects, you have an array with 100 instances of null. You need it iterate over the array, and say

myArray[x] = new gcnew tank();

to create the actual objects in the array.

where x is the index into the array ( you'd probably do this in a loop )

Re: Error with 'System.NullReferenceException'

prasad_som19-Feb-07 3:11

prasad_som

19-Feb-07 3:11

Christian Graus wrote:
myArray[x] = new gcnew tank();

Typo.

Prasad
Notifier using ATL | Operator new[],delete[][^]

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