// 3/27/2014
// we typed this together in class to practice using functions and arrays
#include <iostream>
#include <fstream>
using namespace std;

//prototypes
int sum2nums(int, int&);
void printarray(int[],int);
int sumarray(int[], int);
bool comparearrays(int[], int[], int);
double avgarray(int [], int);
int findmax(int[], int);
int findmin(int [], int);
void findmaxmin(int [], int, int&, int&);
void multby2(int [], int);
void readdata(int [], int);

/* LAB 1 for today:
Write a function that accepts an integer array and a size, and
returns the sum of all the elements in the array. */
/* time permitting:
Write a function called compare that will accept 2 arrays and a
size, and will return true or false. true if the 2 arrays are
identical and false if any value differs.
LAB 2 for today:
Write a function that returns the range of values in an array.
note: the range is a positive number which equals max-min
*/

int main()
{
    int num1=10, num2=12;
    int numelts;
    const int SIZE=10;
    int arr[SIZE];

    cout << "How many elements do you want to input? ";
    cin >> numelts;
    readdata(arr, numelts);

    cout << "The sum of num1 and num2 is: " << sum2nums(num1,num2) << endl;
    // passing individual array elements to a function
    if (numelts>1)
        cout << "The sum of elt 0 and elt 1 is: " << sum2nums(arr[0],arr[1]) << endl;

    // function call passing an array -- NO BRACKETS -- just name of array
    printarray(arr, numelts);
    cout << "The average of the array is: " << avgarray(arr, numelts) << endl;
    int m1, m2;
    findmaxmin(arr, numelts, m1, m2);
    cout << "min is: " << m2 << " max is: " << m1 << endl;

    multby2(arr, numelts);
    cout << "Values after they are multiplied by 2: " << endl;
    printarray(arr, numelts);
    return 0;
}

void printarray(int nums[], int n) {
// nums is an integer array, n is the number of elt in nums
    cout << "In function printarray: ";
    for (int i=0;i<n;i++)
        cout << nums[i] << ' ';
    cout << endl;
}

double avgarray(int arr[], int n) {
// accept an array of size n and return the avg of the values
    double sumvalue=sumarray(arr, n);
    return sumvalue/n;
}

int sumarray(int arr[], int n) {
    int sum=0;
    for (int i=0; i<n; i++)
        sum+=arr[i];
    return sum;
}

int findmax(int arr[], int n) {
    // finds the maximum value of the array arr and returns the value
    int max=arr[0];
    for (int i=0; i<n; i++)
        if (arr[i]>max)
            max=arr[i];
    return max;
}

int findmin(int arr[], int n) {
    // finds the minimum value of the array arr and returns the value
    int min=arr[0];
    for (int i=0; i<n; i++)
        if (arr[i]<min)
            min=arr[i];
    return min;
}

void findmaxmin(int arr[], int n, int &max, int &min) {
// finds both the max and the min and returns them via reference parameters
    min=max=arr[0];
    for (int i=0; i<n; i++) {
        if (arr[i] < min)
            min=arr[i];

        else if (arr[i] > max)
            max=arr[i];
    }

    return;
}

void multby2(int arr[], int n) {
    // multiply every value in the array by 2
    // THIS CHANGES THE ACTUAL VALUES IN THE ARRAY IN THE CALLING FUNCTION
    for (int i=0;i<n;i++)
        arr[i] = arr[i]*2;
}

void readdata(int arr[], int n) {
// read in n data values into array arr
// again, showing that the array is automatically passed by REFERENCE
    for (int i=0; i<n; i++) {
        cout << "Enter a number: ";
        cin >> arr[i];
    }

}
int sum2nums(int x, int &y) {
    // this function returns the sum of its 2 integer parameters
    // we use it here to illustrate passing individual array elements as parameters
    return x+y;
}