// pgm30
// examples of functions that accept arrays as parameters
// 11/16/2016

#include <iostream>
#include <iomanip>
#include <fstream>
#include <cstdlib>
using namespace std;
void displayArray(double[], int);
int readinArray(double[]);
void addTwoArrays(double arr1[], double arr2[], double answer[], int n);
const int SIZE=25;

int main()
{
    // allocate an array of size SIZE
    double idnums[SIZE], numelts=0;
    //initialize an array with { }
    double prices[SIZE], taxes[SIZE]={3.2, 4.1, 1.8, 9, 5.6};
    double total[SIZE];

    // function call to read values into the array
    numelts = readinArray(idnums);
    // function call to display the elts in the array
    displayArray(idnums, numelts);

    // now call readinArray with the prices array
    numelts = readinArray(prices);
    cout << "Prices:";
    displayArray(prices, numelts);
    cout << "Taxes: ";
    displayArray(taxes, 5);

// array assignment is ILLEGAL
//    taxes = {2, 2, 3, 8.1};
//    total = addTwoArrays(prices, taxes, numelts);

    addTwoArrays(prices, taxes, total, numelts);

    cout << "       -----------------------------------------" << endl;
    cout << "Total: ";

    displayArray(total, numelts);

    return 0;
}
// this function accepts an array with n elts.
// It displays the n elts to the screen
void displayArray(double arr[], int n)
{
    //cout << "You entered " << n << " elements. " << endl;
    //cout << "Here is the array: " << endl;
    for (int i=0; i<n; i++)
        cout << setw(8) << fixed << setprecision(1) << arr[i];
    cout << endl;
}

// this function reads values from a file into an array
// the function returns the number of values read in
int readinArray(double nums[])
{
    string filename;
    cout << "Enter name of file: ";
    cin >> filename;
    ifstream inputFile(filename.c_str());
    if (!inputFile) {
        cout << "file did not open.";
        exit(1);
    }
    int n=0; // n stores the number of values read in
    // read in the values into the array
    while (n < SIZE && inputFile >> nums[n]) {

        // Process previous elt (display data)
        //cout << "You entered: " << idnums[numelts] << ' ';
        n++;
        // structured read loop (read in the next piece of data
    }
    inputFile.close();
    return n;
}
// this function accepts two arrays as input (arr1 and arr2)
// it sums each corresponding element and puts the answer
// into the answer array.
void addTwoArrays(double arr1[], double arr2[], double answer[], int n)
{
    for (int i=0;i<n;i++)
        answer[i] = arr1[i] + arr2[i];
}