#include <iostream> // cout, cin, endl
#include <string> // string
#include <cstdlib> // EXIT_SUCCESS
#include <cmath> // round

using namespace std ; // required for cout, cin, endl

void InputArraySize(int &) ;
void InputArrayElements(double [], int) ;
double SumAllArrayElements(double [], int) ;

int main(int argc, char * argv[])
{
    int NumElements = 0 ;
   
    InputArraySize(NumElements) ;

    double Array[NumElements] ;

    InputArrayElements(Array, NumElements) ;

    cout << "Sum of elements = " << SumAllArrayElements(Array, NumElements) << endl ;
    
}

// Pre - None, parameter can have any value
// Post - Asks user for # elements and saves it in parameter
void InputArraySize(int & NumElements)
{
    int counter = 0 ;
    do
    {
	if(counter > 0)
	{
	    cout << "Invalid input: # of Elements must be  > 0" << endl ;
	}
	cout << "Enter number of elements:" ;
	cin >> NumElements ;
	counter++ ;
    }while(NumElements <= 0) ;
}

// Pre - Array has NumElements elements
// Post - Fills Array with the elements, by asking the user for them
void InputArrayElements(double Array[], int NumElements)
{
    for(int i = 0 ; i < NumElements ; i++)
    {
	cout << "Input Array[" << i << "] = " ;
	cin >> Array[i] ;
    }
}

// Pre - Array has NumElements elements
// Post - Sums up all the values and returns it, rounded 2 decimal pts
double SumAllArrayElements(double Array[], int NumElements)
{
    double Sum = 0 ;
    for(int i =  0 ; i < NumElements ; i++)
    {
	Sum += Array[i] ;
    }
    return (round(Sum*100.0) / 100.0) ;
}