Lesson009_18_08_19_Functions

import java.util.Scanner;

public class Lesson009_18_08_19_HomeWork2 {
    private static Scanner sc = new Scanner(System.in);

    public static void main(String[] args) {
        int option = classWorkMenu();
        while (option != 0) {       // while the user didn't put '0', keep pop-up the menu!
            switch (option) {
                case 11:
                    option = task1_1();
                    break;
                case 12:
                    option = task1_2();
                    break;
                case 2:
                    option = task2();
                    break;
                default:
                    System.out.println(option + " is invalid option! try again...\n");
                    option = classWorkMenu();
            }
        }
    }

    public static int classWorkMenu() {
        System.out.print("\n...::: MENU :::...\n" +       // A menu for class tasks
                "From presentation '004_18-08-19 functions' Page 34:\n" +
                "press [11] for task 1.1\n" +
                "press [12] for task 1.2\n" +
                "From presentation '004_18-08-19 functions' Page 35:\n" +
                "press [2] for task 2\n" +
                "press [0] to end this program.\n" +
                "your option is: ");
        int option = sc.nextInt();
        System.out.println();
        return option;          // back to 'Public Static Void Main();'
    }

    // = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
    public static int task1_1() {
        int num, digit;
        System.out.print("Please enter any number: ");
        num = sc.nextInt();
        System.out.print("Please enter any digit: ");
        digit = sc.nextInt();
        System.out.printf("The digit %d in the number %d appears %d times", digit, num, countDigit(num, digit));
        int opt = 0;                    // back to Class Work Menu.
        return opt = classWorkMenu();   // back to Class Work Menu.
    }

    public static int countDigit(int num, int digit) {
        int count = 0;
        do {
            count = num % 10 == digit ? count + 1 : count;
            num /= 10;
        } while (num > 0);
        return count;
    }

    // = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =
    public static int task1_2() {
        int num[] = new int[5], digit;
        for (int i = 0; i < num.length; i += 1) {
            System.out.printf("Please enter a number (%d of %d): ", (i + 1), num.length);
            num[i] = sc.nextInt();
        }   // end for i loop
        System.out.print("Please enter any digit: ");
        digit = sc.nextInt();
        System.out.printf("The digit %d appears %d times in the array\n", digit, countDigitArray(num, digit));
        int opt = 0;                    // back to Class Work Menu.
        return opt = classWorkMenu();   // back to Class Work Menu.
    }

    public static int countDigitArray(int[] num, int digit) {
        int count = 0;
        for (int i = 0; i < num.length; i += 1) {
            count += countDigit(num[i], digit);
        }
        return count;
    }
    // = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =

    public static int task2() {
        int arr1[] = {87, 12, 56, 32};
        int arr2[] = {19, 87, 13, 21, 56};
        int arrNew[] = sameNum(arr1, arr2);
        System.out.println("\nArray 1:");
        for (int i: arr1) { System.out.print(i + " "); }
        System.out.println("\nArray 2:");
        for (int i: arr2) { System.out.print(i + " "); }
        System.out.println("\nNew array:");
        for (int i: arrNew) { System.out.print(i + " "); }
        int opt = 0;                    // back to Class Work Menu.
        return opt = classWorkMenu();   // back to Class Work Menu.
    }
    public static int[] sameNum(int arr1[], int arr2[]) {
        int size = arr1.length > arr2.length ? arr1.length: arr2.length;
        int arrNew[] = new int[size];
        int i=0;
        for (int j = 0; j < arr1.length; j += 1 ) {
            for (int k = 0; k < arr2.length; k += 1 ) {
                if (arr1[j] == arr2[k]) {
                    arrNew[i] = arr1[j];
                    i += 1;
                }   // end if
            }   // end for k loop
        }   // end for j loop
        return arrNew;
    }
}