dev-cpp-users

[Dev-C++] declare a two-dimension array

[Hi, T. <ny_...@ya...>]

Hi, There,

I want to declare a two-dimension array by 
"float coeftemp1 [1024][512];". It doesn't work. 

But, if I change it to "float coeftemp1 [1024][500];".
It works. Could any one know the reason?

Thank you,




//**************************
#include <cstdlib>
#include <iostream>

using namespace std;

int main(int argc, char *argv[])
{
    float coeftemp1 [1024][512];
    system("PAUSE");
    return EXIT_SUCCESS;
}
//**************************



 
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Re: [Dev-C++] declare a two-dimension array

[Per W. <pw...@ia...>]

Don't try to statically allocate huge objects on the stack!

1024*512*4 is 2MB.

Depending on architecture, there are often a limited size the stack may
be.

Depending on architecture and compiler, there is also sometimes a limit to
how much the stack may grow for each function call - it depends on how the
compiler generats code to touch guard pages to let the OS allocate more
memory pages for the stack.

If you want a large array, either allocate it dynamically or create the
array as a global object.

/Per W

On Wed, 13 Dec 2006, Hi, There wrote:

> Hi, There,
>
> I want to declare a two-dimension array by
> "float coeftemp1 [1024][512];". It doesn't work.
>
> But, if I change it to "float coeftemp1 [1024][500];".
> It works. Could any one know the reason?
>
> Thank you,
>
>
>
>
> //**************************
> #include <cstdlib>
> #include <iostream>
>
> using namespace std;
>
> int main(int argc, char *argv[])
> {
>     float coeftemp1 [1024][512];
>     system("PAUSE");
>     return EXIT_SUCCESS;
> }
> //**************************
>
>
>
>
> ____________________________________________________________________________________
> Do you Yahoo!?
> Everyone is raving about the all-new Yahoo! Mail beta.
> http://new.mail.yahoo.com
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Re: [Dev-C++] declare a two-dimension array

[Christoph H. <sha...@ar...>]

Hello,

I had the same problem a while ago, as far as I remember I used new[] to 
get it working.
For example you could use something like that:

    float (*coeftemp1)[512] = new float[1024][512]; //not sure if this 
actually works

or you can use a one dimensional array:

    float *coeftemp1 = new float[1024*512];

and acces it the following way

    float z; //just for testing
    for (int x=0; x<1024; x++){
        for (int y=0; y<512; y++){
           z=coeftemp1[x*y]; //that way it should work
       }
    }

Of course if you don't use c++ you can use malloc. I hope this work, but 
I didn't test it.

Regards,
    Christoph


Hi, There wrote:
> Hi, There,
>
> I want to declare a two-dimension array by 
> "float coeftemp1 [1024][512];". It doesn't work. 
>
> But, if I change it to "float coeftemp1 [1024][500];".
> It works. Could any one know the reason?
>
> Thank you,
>
>
>
>
> //**************************
> #include <cstdlib>
> #include <iostream>
>
> using namespace std;
>
> int main(int argc, char *argv[])
> {
>     float coeftemp1 [1024][512];
>     system("PAUSE");
>     return EXIT_SUCCESS;
> }
> //**************************
>   

[Dev-C++] declare a two-dimension array

[Ahmed H. <ahm...@gm...>]

1024x512 array doesn't allocate so much memory to give an error.
Do you get any error message?

By the way, if you declare a pointer using new operator, you must delete it
before the end.

Re: [Dev-C++] declare a two-dimension array

[Per W. <pw...@ia...>]

For most operating systems, it is not necessary to delete objects before
the application ends. The OS will release all memory allocated to the
program.

However, it is strongly recommended to always release all allocated
memory. By being tidy, it is possible to run memory analyzers to inform
about potential memory leaks, i.e. memory blocks that the program forgets
that it has allocated.

/Per W

On Thu, 14 Dec 2006, Ahmed Han wrote:

> 1024x512 array doesn't allocate so much memory to give an error.
> Do you get any error message?
>
> By the way, if you declare a pointer using new operator, you must delete it
> before the end.
>