system crashes when assigning new value to array

Question

I've posted a similar question to here:

why it crashes when assigning new values to arrays?

But this time, I encountered another problem with arrays again. My code is like this:

double diff[600][800][3];
cv::Mat value ( height, width, CV_8UC3 );
double mean[600][800][3];
....
for ( int i =0; i < 5; ++ i )
{
    for ( int j = 0; j < 3; ++j )
    {
        for ( int m = 0; m < 2; ++m )
        {
            mean[i][j][m] = 10/m;
            diff[i][j][m] = abs ( value.data[value.cols*i+j]-mean[i][j][m]);
        }
    }
}

It crashed at the line:

diff[i][j][m] = abs ( value.data[value.cols*i+j]-mean[i][j][m]);

I even omitted that line, and just wrote it like:

double test = abs ( value.data[value.cols*i+j]-mean[i][j][m]);

and it compiled, then I added

std::cout << test << std::endl;

it again crashed, and this line also crashed:

diff[i][j][m] = test;

I even changed it like this:

double test = static_cast<double>(abs(value.data[value.cols*i+j]-mean[i][j][m]));
diff[i][j][m] = test;

again, crashed. If I write it like:

diff[i][j][m] = 10;

it compiles. I really cannot figure out the problem. Seems like this is not related to stack overflowing, or datatype. I even tried Aki Suihkonen's answer for my previous question, but it couldn't help. Could someone help me find the problem here??

What size is value.data array ? I think you are trying to access some memory you are not allowed to. — tomahh, Oct 06 '12 at 09:34
@ederman, Sure, use `std::vector`. The stack implementations I've seen are generally around 1MB. The heap's much bigger. Being 3D, if you need more efficiency, wrap an underlying 1D vector. — chris, Oct 06 '12 at 09:38
@chris: any example code please, or else mostly I will write it wrong again, and ask again :( I am not very good at writing this. — E_learner, Oct 06 '12 at 09:39
@chris: by the way, how did you calculate almost 3 million? I think that is the part I need to learn. — E_learner, Oct 06 '12 at 09:40
@ederman, For the most part, vectors are like arrays, though a bit more annoying to declare in more than one dimension. There's tons of stuff on vectors out there. They don't perform too well past one dimension either (hence a wrapper). As for almost 3 million, you have 2 arrays of 600*800*3=1440000 doubles each. — chris, Oct 06 '12 at 09:45
@chris: ok, thank you for your answer. I want to select yours as best answer, but it is in the comments part :( — E_learner, Oct 06 '12 at 10:51
@chris: I tried using miltidimensional vectors, but it is too much slow to me. Also, it crashed after several seconds of running. Isn't there any other way to improve this? — E_learner, Oct 06 '12 at 12:13
@ederman, Yes, maybe you forgot to change the division by 0 when using vectors. A debugger would be a good start to figuring out where and why the crash happens. As for multidimensional vector performance, you can make yourself a `Matrix3D` class which contains a 1D vector of length `dimA * dimB * dimC` and make it behave as if it was 3D (an easy way is to use `operator()` to provide `diff(5, 3, 1)` accessing functionality). — chris, Oct 06 '12 at 15:50

score 2 · Accepted Answer · answered Oct 06 '12 at 10:56

2

    for ( int m = 0; m < 2; ++m )
    {
       mean[i][j][m] = 10/m;
       //...
     }

This leads to division by zero for value of m =0 .. Possibly the reason of crash.

answered Oct 06 '12 at 10:56

bhuwansahni

1,784
1
11
20

@bhuwanshni: I don't think so, even I tried giving a constant value like "25", it also crashed. Do you have any other idea? – E_learner Oct 06 '12 at 12:14

score 1 · Answer 2 · answered Jul 30 '15 at 01:02

Probably double diff[600][800][3]; is too big for your system's default stack size. If you have 64-bit doubles then this is 11.5MB, whereas many compilers default to a 1MB stack size.

Try static double diff[600][800][3]; instead , and the same for your other large array.

If you really need the arrays to be non-static (i.e. if the function is re-entrant) you will need to use dynamic allocation.

system crashes when assigning new value to array

2 Answers2