I work with a large two-dimensional array.

In the case when it is 30 x 200, everything is considered. With large volumes, the program crashes … I was advised to use MemSet (), but something does not particularly help …
Maybe you have any ideas?

# include & lt; stdio.h & gt;
#Include & lt; stdlib.h & gt;
#Include & lt; math.h & gt;
#Include & lt; String.h & gt;
Double ** B;
Int Main (int argc, char * argv [])
{
  int n, n_a;
  N = 32;
  n_a = 350; / * If you do n_a = 200, then everything works * /
  B = (Double **) Malloc (N * Sizeof (Double *));
  for (i = 0; i & lt; n; i ++)
  {
    B [i] = (Double *) Malloc (N_A * SizeOF (Double));
    Memset (B [i], 0, N_a * Sizeof (Double));
  }
  FREE (B);
  Return 0;
}

Answer 1, Authority 100%

In general, the code is correct, but you need to add a check when the memory is allocated: this is necessary, because the memory may simply miss, and in this case the program will fall, because it will be recorded in non-existent memory. That is, whenever Malloc calls, it is necessary to verify that the return value is not equal to NULL.

B = (Double **) Malloc (N * Sizeof (Double *));
/ * Check that the memory is allocated * /
If (b! = NULL)
{
  for (i = 0; i & lt; n; i ++)
  {
    B [i] = (Double *) Malloc (N_A * SizeOF (Double));
    / * Check that the memory is allocated * /
    IF (B [i]! = NULL)
    {
      Memset (B [i], 0, N_a * Sizeof (Double));
      FREE (B [i]);
    }
  }
  FREE (B);
}

In addition, you must not forget to release the memory allocated by Malloc inside the cycle, otherwise there will be leaks.

Answer 2, Authority 25%

That’s all you can make one line

double * b;
B = (Double *) Calloc (N * N_A, SizeOF (Double));
FREE (B);

Instead of calling a heap of functions, you call one that immediately highlights the memory of the entire data array and reset it.

data access is carried out by the

formula

double a;
a = * (b + i * n_a + j);

where i – line number, j – column number

Answer 3

With large volumes, the program crashes …

Local buffer (more precisely, the size of the stack frame) should not have the size of a larger one page. Otherwise, it will take place beyond the limits of the stack watchdog, it will not be expanded and an exception will arise.