How to get the size of dynamically allocated 2d array

Question

I have dynamically allocated 2D array. Here is the code

int **arrofptr ;
arrofptr = (int **)malloc(sizeof(int *) * 2);
arrofptr[0] = (int *)malloc(sizeof(int         


        

Answer 1

if you want to keep track of the size of an allocated block of code you would need to store that information in the memory block that you allocate e.g.

// allocate 1000 ints plus one int to store size

int* p = malloc(1000*sizeof(int) + sizeof(int)); 
*p = (int)(1000*sizeof(int));
p += sizeof(int);

...

void foo(int *p)
{
  if (p)
  {
    --p;
    printf( "p size is %d bytes", *p );
  }
}

alt. put in a struct

struct
{
  int size;
  int *array;
} s;