count elements in a vector

Get number of elements in a Vector using C++
cpp code

#include <iostream>
using std::cout;
using std::endl;

#include <algorithm>
#include <numeric>
#include <vector>
#include <iterator>

int main()
{
   std::ostream_iterator< int > output( cout, " " );

   int a2[ 10 ] = { 100, 2, 8, 1, 50, 3, 8, 8, 9, 10 };
   std::vector< int > v2( a2, a2 + 10 ); // copy of a2
   cout << "Vector v2 contains: ";
   std::copy( v2.begin(), v2.end(), output );

   // count number of elements in v2 with value 8
   int result = std::count( v2.begin(), v2.end(), 8 );
   cout << "\nNumber of elements matching 8: " << result;

   cout << endl;
   return 0;
}

/* 
Vector v2 contains: 100 2 8 1 50 3 8 8 9 10
Number of elements matching 8: 3

 */