store Array values until next time method called

[jotartub]

Hi.
Does anyone know how can i crate an Array not managed, and it doesn't looses his contents.
My problem is:
I've a method that returns a managed array and i want to store it but i can't store it in a CollectionBase List cause the system throws me an exception stack overflow, my method is called in timer_tick.
Does anyone know how can i store that array until the next tick to compare them?
thanks

[weaknessforcats]

I expect you need to create the array on the heap rather than the stack. Stack memory is often limited.

int arr[10000];     //bad
int* arr = new int[10000];    //good
 

If this doesn't work, or you are already doing this, then a code snippet would be appreciated.

[jotartub]

My problem is that i want to store the values froma a matrix that are xomputed in a method then when i repeat that method i want to have them avaiable again and subtract them from a new matrix. is like;
method(MatrizIPF)
MatrizIPF[i,j]=a;
MatrizINPF[i,j]=0;

MatrixA=MatrizIPF;
return MatrizIPF

and then call again the method
and do

MatrixA-MatrixIPF;

MatrixA=MatrixIPF;
RETURN MatrizIPF;

IS THIS MORE OR LESS

[Banfa]

Stack memory is often limited.

I've seen you say this a few times (in various guises) now. However in my experience if stack space is limited then so is heap space (i.e. on an embedded platform) and if heap space is not particularly limited then neither is the stack space (on the Windows platform). I admit I have no knowledge of *nix platforms in this regard. This seems to stem from the fact that both are allocated from available RAM (physical and virtual in some cases) and therefore space in these segements are both ultimately dependent on the amount of RAM available on the platform and have similar limits.

While I have seen some interesting arguments on whether it is better to allocate from the stack or heap it appears to me that "because stack space is more limited than heap space" is not a particularly good one.

[weaknessforcats]

However in my experience if stack space is limited then so is heap space (i.e. on an embedded platform) and if heap space is not particularly limited then neither is the stack space (on the Windows platform). I admit I have no knowledge of *nix platforms in this regard.

My sole experience with this was a big Unix box running HP-UX. The stack was limited to 4096 bytes and it took a signature from a third-level manager and concurrence from the sysadmin to allow you to have more space.

The phenomenon was a run-time crash.

If you are saying that the stack will expand as necessary and that this HP-UX box (at Boeing) was an anomaly, then I will not say that again.

[Banfa]

My sole experience with this was a big Unix box running HP-UX. The stack was limited to 4096 bytes and it took a signature from a third-level manager and concurrence from the sysadmin to allow you to have more space.

The phenomenon was a run-time crash.

If you are saying that the stack will expand as necessary and that this HP-UX box (at Boeing) was an anomaly, then I will not say that again.

Well that rather explains your statement.

I am saying the stack and heap sizes are platform dependent.

For instance on Windows the thread stacks are initially 20k bytes but will grow up to the limit of available RAM as required, I am not sure what the intiial heap size is but it too will grow as required to the limit of available RAM.

Generally on embedded platforms the stack and heap sizes are defineable. On the platform I am currently using I have a 256 byte stack and a 30k byte heap, however the stack is only used to run the background task of the RTOS, the the main working tasks then have their stacks allocated from the heap.

On another embeddd platform I have worked on the stack was been 4k bytes but the heap only 2k bytes (this was written in C and allocating space from heap was specifically prohibited), again RTOS tasks then have their own stacks too, these were allocated as static arrays of char.

Anyway stack and heap sizes are platform dependent and can be under the control of the prgrammer sometimes. Your HP-UX box is not an anomily it is just 1 way of having the stack and heap organised.

[gsi]

Hi,

store the values froma a matrix that are xomputed in a method then when i repeat that method i want to have them avaiable again

Simplest workaround is to declare the 2 dimensional array(matrix) as a seperate class member or make it static inside the method.

thanks,
gsi.

[weaknessforcats]

Simplest workaround is to declare the 2 dimensional array(matrix) as a seperate class member or make it static inside the method.

This is the same as declaring a global variable. Only the scope is different.

There are no good reasons for using global variables.

In this case, the array should be a class private member and the class should have methods to work with the array. When an obect of the class is created, it is passed to functions using a handle. See this article in the C/C++ Articles forum.

[gsi]

Hi,

There are no good reasons for using global variables.

That's right. Sorry for the misleading info.

Thanks,
gsi.

[jotartub]

I think i haven't explained very well my problem, i'll post my code here and i'll try to explain it.


private: System::Void timer1_Tick(System::Object * sender, System::EventArgs * e)
{

h=this->axXVideoOCX1->XGetImageHeight(imagehandle);
w=this->axXVideoOCX1->XGetImageWidth(imagehandle);
int MatrizIPF[,] = new int __gc[h,w];
int MatrizINPF[,] = new int __gc[h,w];
int MatrizVIPF[,] = new int __gc[h,w];
int MatrizVINPF[,] = new int __gc[h,w];
int teste __gc[,];
int teste2 __gc[,];

if(condition)
{

MatrixPixeisdeFogo(pixels,h,w,MatrizIPF);

}
else
{
this->textBox3->Text=" ";
}
}

int MatrixNPixeisdeFogo(unsigned char *pixels, int h, int w, int MatrizINPF __gc[,])[,]
{
if(condition)
{
MatrizINPF[i,j]=0;
}
}
else
{
MatrizINPF[i,j]=a;
}
delete crgb;
}
}
MatrizVINPFI=MatrizINPFI-MatrizINPF;
MatrizINPFI=MatrizINPF;
return something;
}

so what i would like to learn is how can i keep in MatrizINPFI the past value of MatrizINPF, is to compute the Variation of it in MatrizVINPFI.
Is it clear?

[jotartub]

ystem.NullReferenceException: A referência de objecto não foi definida como uma instância de um objecto.
at DetectordeIncendios.Form1.MatrixPixeisdeFogo(Byte* pixels, Int32 h, Int32 w, Int32[,] MatrizIPF) in c:\documents and settings\proprietário-de-hp\ambiente de trabalho\pedro\projecto\detector de incendios prototipoii\form1.h:line 452
at DetectordeIncendios.Form1.timer1_Tick(Object sender, EventArgs e) in c:\documents and settings\proprietário-de-hp\ambiente de trabalho\pedro\projecto\detector de incendios prototipoii\form1.h:line 332
at System.Windows.Forms.Timer.OnTick(EventArgs e)
at System.Windows.Forms.Timer.Callback(IntPtr hWnd, Int32 msg, IntPtr idEvent, IntPtr dwTime)