How to count the number of elements in an array?

Question

C++ / C#

something similar to

#include <stdio.h>
#include <iostream>
#include cstddef 
 
using namespace std;
  
int main()
{
 
    int mas[] = { 1, 2, 3 };
    cout << sizeof(mas) << endl;

    return 0;
}

Answer 1

In such a variant.
sizeof (mas) / sizeof(mas[0])
But don't do that

Answer 2

std::size(mas)
or But is better to use in general. It has a size method.
std::array

Answer 3

You can stop like this a little under the 11th standard
#include < array > // remove spaces
using namespace std;
array i_arr;
cout << "i_arr size: " << i_arr.size() << endl