passing array as ref to maintain size info in C++

find_duplicates_in_unsorted_array.cpp

// If std::array is not an option (e.g embedded), use the following tactic to maintain size info of array as param
// This method uses non-type template arguments to retain size of array.
// See std::begin() and std::end() for similar approaches.


#include <iostream>
using namespace std;

// @param h {T} represents highest number in given array
// used to determine size of hash array
template<typename T, size_t N>
void findDups(T (&a)[N], T h) // pass array of N refs (&a)
{
  T *hashArr = new T[h]{0}; // zero-initialized on heap

  for(int i = 0; i<N; i++)
    hashArr[a[i]]++;

  for(int j = 0; j <= h; j++)
    if(hashArr[j] > 1)
      cout << j << ":" << hashArr[j] << endl;
}

template<typename T, size_t N>
T ArraySum(T (&arr)[N])
{
  T sum = 0;
  for(auto el: arr)
    sum += el;

  return sum;
} 


int main()
{
  int arr[10] = {8,3,6,4,6,5,6,8,2,7};

  // 8 represents highest number in arr
  findDups(arr, 8);
  
  // same principle to sum array
  float f_arr[]{ 2.1212f,1.1f,3.23f,4.5f };
  auto farray_sum = ArraySum(f_arr); // passing array is enough. no extra size_t param needed.
  cout << "Float Array sum: " << farray_sum << endl;


  return 0;
}