Is there any way to determine the size of a C++ array programmatically? And if not, why?

int* arr = new int[256];
printf("Size of arr: %dn", sizeof(arr));

int *arr = new int[256];
int *p = &arr[100];
printf("Size: %dn", sizeof(p));

int main()
{
   std::vector<int> v(256);
   printf("size of v is %i capacity is %in", sizeof(int) * v.size(), sizeof(int) * v.capacity());
}

const int arrSize = 256;
int main()
{
    int array[arrSize];
    printf("Size of array is %i", sizeof(int) * arrSize);
}

string* p = new string[5];
delete[5] p;

size_t* p = new size_t[10];
cout << p[-1] << endl;
// Or
cout << p[11] << endl;

char *ar = new char[100]