// 11/18/2019
// Wrote several methods to process arrays:
// changeArray, find max, find max index, find max of 2 arrays
// sum all values in an array, read values into an array

import java.util.Scanner;

public class ArrraysandMethods {
  public static void main(String[] args) {
   
    int[] numbers = {4, 6, 8, 10, 12};
    
    // some examples of methods and arrays
    changeArray(numbers);
    System.out.println(numbers); // this will not print the whole array
    for (int num : numbers)
      System.out.println(num);
    int sum = sumArray(numbers);
    System.out.println("Sum is: " + sum);
    int max = maxValue(numbers);
    System.out.println("Max is: " + max);
    int numElts = readArray(numbers);
    
    for (int i=0; i<numElts; i++)
        System.out.print(numbers[i] + " ");
    System.out.println(numElts + " numbers were read in."
        + " That is the # of elements in the array.");
  }
  /** changeArray
    */
  public static void changeArray(int[] arr) {
    for (int i=0; i<arr.length; i++)
      arr[i]*=2;
  }
  /** sumArray
    */
  public static int sumArray(int[] arr) {
    int sum = 0;
    for (int i=0; i<arr.length; i++)
      sum+=arr[i];
    return sum;
  }
  /** maxValue finds max in arr 
    * @param arr integer array
      @return max VALUE */
  public static int maxValue(int[] arr) {
    int max = arr[0];
    for (int i=1; i<arr.length; i++) {
      if (arr[i] > max) {
        max = arr[i];
      }
    }
    return max;
  }
  /** maxIndex finds max in arr and returns the INDEX of
    * the max value */
  public static int maxIndex(int[] arr) {
    int max = arr[0];
    int maxIndex = 0;
    for (int i=1; i<arr.length; i++) {
      if (arr[i] > max) {
        max = arr[i];
        maxIndex = i;
      }
    }
    return maxIndex;
  }
  /** this shows that you no longer need variable max
    int maxIndex = 0;
    for (int i=1; i<arr.length; i++) {
      if (arr[i] > arr[maxIndex]) {
        maxIndex = i;
      }
    }
  /**
    return maxIndex;
  /** maxValue2 finds largest value in 2 arrays
    */
  public static int maxValue2(int[] arr1, int[] arr2) {
    int max = arr1[0];
    for (int i=1; i<arr1.length; i++) {
      if (arr1[i] > max) {
        max = arr1[i];
      }
    }
    // now max has the max value in arr1
    for (int i=0; i<arr2.length; i++) {
      if (arr2[i] > max) {
        max = arr2[i];
      }
    }
    return max;
  }
  /** @return the number of elts read into the array */
  public static int readArray(int[] numbers) {
    Scanner sc = new Scanner(System.in);
    int counter = 0;
    System.out.println("Enter a #, ^D to exit:");
    while(sc.hasNextInt()  && counter < numbers.length) {
      numbers[counter]=sc.nextInt();
      counter++;
    }
    return counter;
  }
}