Small C snippet to have a dynamically allocated array (only few operations)

dyn array.c

struct flt_array;
typedef void (*flt_array_growpolicy)(flt_array*);
typedef struct flt_array
{
  void** data;
  int size;
  int capacity;
  flt_array_growpolicy growpolicy;
}flt_array;


int flt_array_create(flt_array** arr, int capacity, flt_array_growpolicy grow)
{
  *arr = (flt_array*)flt_calloc(1,sizeof(flt_array));
  if ( !*arr ) return FLT_FALSE;
  (*arr)->capacity = capacity>0?capacity:FLT_ARRAY_INITCAP;
  (*arr)->size = 0;
  (*arr)->data = (void**)flt_malloc(sizeof(void*)*capacity);
  if ( !(*arr)->data ) { flt_array_destroy(arr); return FLT_FALSE; }
  if ( !grow ) grow = flt_array_grow_double;
  (*arr)->growpolicy = grow;
  return FLT_TRUE;
}

void flt_array_destroy(flt_array** arr)
{
  if ( !arr || !*arr ) return;
  flt_safefree((*arr)->data);
  flt_free(*arr);
  *arr=FLT_NULL;
}

void flt_array_grow_double(flt_array* arr)
{
  int newcap = arr->capacity*2;
  arr->data = (void**)flt_realloc(arr->data, sizeof(void*)*newcap);
  if( !arr->data ) { FLT_BREAK; return; }
  arr->capacity = newcap;
}

void flt_array_push_back(flt_array* arr, void* elem)
{
  if (arr->size>=arr->capacity)
    arr->growpolicy(arr);    
  arr->data[arr->size++]=elem;
}

void* flt_array_pop_back(flt_array* arr)
{
  if ( arr->size==0 ) return FLT_NULL;
  return arr->data[--arr->size];
}

void* flt_array_at(flt_array* arr, int index)
{
  return index >= 0 && index < arr->size ? arr->data[index] : FLT_NULL;
}

void flt_array_clear(flt_array* arr)
{
  arr->size=0;
}