Stack overflow C++

Question

This is my code. When I access dtr array in initImg function it gives a stack overflow exception. What might be the reason?

#define W 1000
#define H 1000
#de         


        

Answer 1

You will eventually get to

dtr[W*W+j] = 0;   <------here

Which is much more than you have allocated.

Answer 2

In addition to the stack overrun, you have another problem -- one which is masked by your definitions of W and H.

for(int i=0;i<W;i++)
    for(int j=0;j<H;j++)
    { 
        if(img[i*W+j]==0)
            dtr[i*W+j] = 0;    // <------here
        else
            dtr[i*W+j] = MAX;  // <------here
    }

Your i loop should count from 0 to H-1, rather than W-1 (and the j loop should swap as well). Otherwise your code will only work correctly if W==H. If WH you will overrun your buffers.

This same problem exists elsewhere in your code sample as well.