We Keep Coding

To find out Armstrong number in between numbers

Below is my code.
package com.ofss.java.examples;
import java.util.Scanner;
class ArmstrongNumber {
public static void main(String[] args) {
int c = 0, a;
int n1, n2;//Range in which armstrong number need to find
Scanner s = new Scanner(System.in);
System.out.println("Enter the first number");
n1 = s.nextInt();
System.out.println("Enter the second number");
n2 = s.nextInt();
for (int i = n1; i <= n2; ++i) {
while (i > 0) {
a = i % 10;
System.out.println(a);
i = i / 10;
System.out.println(i);
c = c + (a * a * a);
System.out.println(c);
}
if (i == c)
System.out.println(c + "armstrong number");
else
System.out.println(c + "Not armstrong number");
}
}
}
I am getting incorrect results after executing. Code runs for infinite number till you stops it. It must print number between 151-154 (153 as armstrong).
Also, it is incorrectly printing 153 as not Armstrong number.
Armstrong Number
...is a number that is the sum of its own digits each raised to the power of the number of digits.

You should not change i since this is also used in
for (int i = n1; i <= n2; ++i)
Or you will probably never exit that loop eiter since you expect i to be negative at the end of the first iteration. Hard to increment until it reach n2.
Use a different variable to keep track of i safely.
int j = i;
while(j > 0) ...
About Armstrong number:
Armstrong number is a number that is the sum of its own digits each raised to the power of the number of digits
You need to put each digit to the power of the length of the number (the number of digit).
153 = 1^3 + 5^3 + 3^3
1634 = 1^4 + 6^4 + 3^4 + 4^4
Here is the method for it :
public static boolean isArmstrongNumber(int number){
int power = Integer.toString(number).length(); //just to get the number of digit...
int tmp = number;
int digit , sum = 0;
while(tmp > 0){
digit = tmp % 10;
sum += Math.round(Math.pow(digit , power));
tmp /= 10;
}
return sum == number;
}
Using this check from 0 to 10.000 gives :
0
1
2
3
4
5
6
7
8
9
153
370
371
407
1634
8208
9474
Same as Wikipedia :
The sequence of base 10 narcissistic numbers starts: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 153, 370, 371, 407, 1634, 8208, 9474, ...
Note that using a method remove the risk of forgetting to reset your variable like c in your case. Correcting this would give you a few more "correct" results (well the one with 3 digits)
You can also use less mathematics to read the number and use char[], remember that you need to substract '0' value to get the numeric value for a character :
public static boolean isArmstrongNumber(int number){
char[] digits = Integer.toString(number).toCharArray();
int power = digits.length;
int sum = 0;
for(char c : digits){
int digit = c - '0';
sum += Math.round(Math.pow(digit, power));
}
return sum == number;
}

There are two things.
you are updating i everytime as you have used it in while, so use different variable than i for this calculation.
int num = i;
c is used to compare sum of cube is same as number but you are not resetting it once the one iteration is over. so make c=0 inside for loop.
c = 0;
Also while printing you are using c, there should be i which is correct and real number.
Below is the working code you may try.
public static void main(String[] args)
{
int c = 0, a;
int n1, n2;//Range in which armstrong number need to find
Scanner s = new Scanner(System.in);
System.out.println("Enter the first number");
n1 = s.nextInt();
System.out.println("Enter the second number");
n2 = s.nextInt();
for (int i = n1; i <= n2; ++i)
{
int num = i;
while (num > 0)
{
a = num % 10;
num = num / 10;
c = c + (a * a * a);
}
if (i == c)
System.out.println(i + "armstrong number");
else
System.out.println(i + "Not armstrong number");
c = 0;
}
}

public class ArmstrongNumber {
private final int n1, n2;
public ArmstrongNumber(int n1, int n2) {
this.n1 = n1;
this.n2 = n2;
}
protected static boolean isArmstrong(int n) {
if(n < 0)
return false;
int remaining=n;
int sumCube=0;
while (remaining>0) {
int d = remaining % 10;
sumCube += cube(d);
remaining /= 10;
}
return n == sumCube;
}
private static int cube(int d) {
return d*d*d;
}
public Integer[] find() {
List<Integer> results = new ArrayList<>();
for (int i = n1; i <= n2; ++i)
{
if (isArmstrong(i))
results.add(i);
}
return results.toArray(new Integer[0]);
}
}

There are lot of things to improve in your code. One of the working logics as below:
for (int i = n1; i <= n2; ++i) {
int sum = 0, remainder = 0, digits = 0, temp = 0;
temp = i;
while (temp != 0) {
digits++;
temp = temp / 10;
}
temp = i;
while (temp != 0) {
remainder = temp % 10;
sum = sum + (int) Math.pow(remainder, digits);
temp = temp / 10;
}
if (i == sum)
System.out.println(i + " is an Armstrong number.");
else
System.out.println(i + " isn't an Armstrong number.");
}

Multiple the sum of digit of a number

I am having a hard time figuring out the solution to this problem. I need to write a program that gets an input n (via scanner), then goes with a for loop till that input number, checks if the numbers are divisible by 13 and then multiplies the digits of each number.
So for an example, if the input number is 40, the divisible numbers by 13 would be 13, 26, 39
1+3 = 4,
2+6 = 8,
3+9 = 12
so that's 4*8*12 = 384.
My current code, but I'm stuck here. I probably didn't do it right, too:
Scanner myScanner = new Scanner(System.in);
int num = myScanner.nextInt();
int sum = 0;
for (int i = 0; i < 30; i = i + 1) {
if (i % 13 == 0) {
while (i > 0) {
int add = i % 10;
sum = sum + add;
i = i / 10;
}
}
}

You're computing the sum of the digits, not the product. Also, you're loop is going to 30, not to num. (There's also no reason to start the loop at 0 instead of 1.) Finally, you shouldn't be changing i inside the loop itself; that will screw up the iteration logic. Use an auxiliary variable. Something like this (untested) should work:
Scanner myScanner = new Scanner(System.in);
int num = myScanner.nextInt();
int prod = 1;
for (int i = 1; i < num; i++) {
if (i % 13 == 0) {
int j = i,
sumOfDigits = 0;
while (j > 0) {
int digit = j % 10;
sumOfDigits += digit;
j /= 10;
}
prod *= sumOfDigits;
}
}

Your whole code is messy. You need to work more on loops and variable assignments and scopes.
Given below is the correct code.
Scanner myScanner = new Scanner(System.in);
int num = myScanner.nextInt();
int mul = 1;
for (int i = 1; i < num; i = i + 1) {
if (i % 13 == 0) {
int sum = 0;
int number = i; // = some int
while (number > 0) {
sum = sum + (number % 10);
number = number / 10;
}
mul = mul * sum;
}
}
System.out.println(mul);
myScanner.close();

Another way to do it, change the number that are divisible to char array, then add and multiply.
Scanner sc=new Scanner(System.in);
System.out.println("Enter a number: ");
int num = sc.nextInt();
int prod = 1;
for (int i = 1; i < num; i++) {
if (i % 13 == 0) {
String number = String.valueOf(i);
char[] digits1 = number.toCharArray();
int sum = 0;
for (char ii:digits1) {
sum = Character.getNumericValue(ii) + sum;
}
prod = prod*sum;
}
}
System.out.println(prod);

Java lottery using arrays

I have to create a lottery game where you randomly generate six winning numbers simulating a lottery. Ask the user to enter six numbers and see if they win the lottery!
I have done a lot of it, but now im stuck. I am really new to java so forgive me. When it prompts to ask for another number it does it but it still displays it for the self-made lottery picks that display. Also, when displaying the numbers for the computer made lottery picks they are the same numbers over again that repeat and aren't 6 numbers. The counter doesn't work as well it maybe a little thing but i can't figure it out. Thank you
package arraysIntroduction;
import java.util.Scanner;
public class sizeQuestion {
public static void main(String[] args) {
Scanner in = new Scanner (System.in);
int [] user =new int [6];
int i;
//Fill user array
System.err.println("Welcome to Miwand's Lottery");
System.out.println("Please enter your 6 desiered number to enter the lottery");
System.out.println("Pick from 1 to 49");
for ( i=0;i<user.length;i++) // gets numbers until it equals 6
{
System.out.println("Number:");
user[i]= in.nextInt(); // Gets numbers from user
while (user[i] < 0 ) // if its a negative number tell user to enter again
{
System.err.println("Negative number, please enter again:");
user[i]=in.nextInt();
}
if (user[i] > 49) // if the number goes past 49 prompt again
{
System.err.println("Please enter numbers from 1 - 49");
}
}
//print out the numbers generated
for ( i=0;i < user.length; i++){
System.out.print(+user[i]+ " ");
}
System.out.println(" ");
int[] lottery = new int[6];
int guesses;
int counter=0;
int j;
int x;
{
for (j = 0; j < 6; j++) {
int randomNum = (int) (Math.random() *49 +1); // Random number created here.
for ( x = 0; x < j; x++) {
if (lottery[x] == randomNum) // Here, code checks if same random number generated before.
{
randomNum = (int) (Math.random() *49 +1);// If random number is same, another number generated.
}
lottery[j] = randomNum;
}
}
//prints out computer generated numbers
for (i = 0; i < lottery.length; i++){
for (x = 0; x< j; x++){
System.out.print(lottery[i] + " ");
if (user[i] == lottery[x] ){
counter++;
}
}
}
}
if (counter < 2){
System.out.println("Try again!");
}
if (counter == 3){
System.out.println("3 numbers matched! You won $300!");
}
if (counter == 4){
System.out.println("4 numbers matched! You won 500!");
}
if (counter == 5){
System.out.println(" 5 numbers matched! You won $1000!");
}
else if (counter == 6){
System.out.println("JACCKKKPOOOOTTTTTTT!!!!!! YOU WIN 1 MILLION DOLLARS!");
}
}
}

I saw multiple problems in your program.
First, the printout problem can be solved by moving the print statement from inner loop to outer loop
for (i = 0; i < lottery.length; i++) {
System.out.print(lottery[i] + " ");
for (x = 0; x < j; x++) {
if (user[i] == lottery[x]) {
counter++;
}
}
}
Also, you are not assigning the first random number correctly and it is always using the default, which is 0
Solution:
for (j = 0; j < 6; j++) {
int randomNum = (int) (Math.random() * 49 + 1); // Random number created here.
for (x = 0; x < j; x++) {
if (lottery[x] == randomNum) // Here, code checks if same random number generated before.
{
randomNum = (int) (Math.random() * 49 + 1);// If random number is same, another number generated.
}
}
lottery[j] = randomNum;
}
Plus, you didn't check if counter is equal to 2
Solution:
if (counter <= 2) {
System.out.println("Try again!");
}
And, the logic in "If random number is same, another number generated." may not be correct, since it may generate the same number again. You need a while loop to generate a new number until it is not equal to any of the generated numbers.
Another thing about coding style is that for any "for loops"
This :
int i=0;
for (i = 0; i < length; i++)
Should be replaced by this:
for (int i = 0; i < length; i++)

As I already said in the comments, you should move the print statement from the inner loop to the outer loop.
Your code should look like this:
for (i = 0; i < lottery.length; i++) { // outer loop
System.out.print(lottery[i] + " ");
for (x = 0; x < j; x++) { // inner loop
if (user[i] == lottery[x]) {
counter++;
}
}
}

How to calculate the average of even and odd numbers in an array?

As a class exercise I have to code using methods a program that:
1) Calculates the average of even and odd numbers in an array.
I expect on using one method to find the average of even and odd numbers. However, I'm having trouble on returning the right average. For example, if I enter only odd numbers I get an error, and vice versa.
This error:
"java.lang.ArithmeticException: / zero"
Also, if it were possible I would like to get some help on coding the rest of the exercise which asks for:
2) Print the highest and lowest number in the array
3) Allow the user to modify any of the numbers of the array
So far I have this code:
public static void main (String args[]){
int x[] = new int[4];
Scanner input = new Scanner(System.in);
for(int i = 0; i < x.length ; i++){
System.out.println("Enter a number: ");
x[i] = input.nextInt();
}
System.out.println("Average of even numbers: " + getAverage(x));
System.out.println("Average of odd numbers: " + getAverage(x));
}
public static int getAverage(int a[]){
int add_even = 0;
int counter_even = 0;
int average_even = 0;
int add_odd = 0;
int counter_odd = 0;
int average_odd = 0;
for(int i = 0; i < a.length; i++){
if(a[i] % 2 == 0){
add_even += a[i];
counter_even++;
}
else if(a[i] % 2 == 1) {
add_odd += a[i];
counter_odd++;
}
}
if (add_even % 2 == 1 && add_odd % 2 == 1){
average_even = 0;
average_odd = add_odd / counter_odd;
return average_even;
}
else if (add_even % 2 == 0 && add_odd % 2 == 0){
average_even = add_even / counter_even;
average_odd = 0;
return average_even;
}
else{
average_even = 0;
average_odd = add_odd / counter_odd;
return average_odd;
}
}
Thank you!

Your get average looks more complicated then it needs to be.
First off the getAverage(x):
System.out.println("Average of even numbers: " + getAverage(x));
System.out.println("Average of odd numbers: " + getAverage(x));
will return the same value, so if you wanted to get the average for odds or evens the method should require a boolean arg to represent odd or even.
In your method you should loop through all the numbers and check if it is even. If it is even and you are averaging evens add it to a "total" and add one to a counter. At the end divide "total" by the counter and return the value. The average will most likely include a decimal value, so you should return a double or a float.
Example:
public static double getAverage(int a[], boolean even){
double total = 0;//These are doubles so dividing later does not require casting to retain a decimal (this can be an int if you only want to return integers)
double counter = 0;
for(int i = 0; i<a.length; i++){
if(a[i] % 2 == 0 && even){//even
counter++;
total += a[i];
}else{//odd
counter++;
total += a[i];
}
}
if(total == 0){//Avoid dividing by 0.
return 0; //You can also throw an exception instead of returning 0.
}
return total / counter; //Returns the average for even or odd numbers.
}
For the second part of your question you need to loop through the numbers and find the highest and lowest while looping.
Example:
int highest = 0;
int lowest = 0;
for(int i = 0; i<x.length; i++){
if(x[i] > highest){
highest = x[i];
}
if(x[i] < lowest){
lowest = x[i];
}
if(i == 0){
highest = x[i];
lowest = x[i];
}
}

You have a divide by zero error cropping up here.
else if (add_even % 2 == 0 && add_odd % 2 == 0){
average_even = add_even / counter_even;
average_odd = 0;
return average_even;
}
0 % 2 == 0 so even if add_even is 0 (and as a result, so is counter_even) you're attempting to use it to divide. You'll need to account for that in your code by checking if counter_even is 0.
else if (counter_even != 0 && add_even % 2 == 0 && add_odd % 2 == 0){

1)Using one method to get the average of the even and odd numbers isn't proper because you only return one int. It would be simpler to use two methods but if you're insistent on using one method you could add a boolean as a parameter like this to decide which to do. To handle the ArithmeticException just return 0 if there are no values.
public static int average(int[] n, boolean even) {
int total = 0;
int count = 0;
for (int i = 0; i < n.length; i++) {
if (even == (n % 2 == 0)) {
total += n;
count ++;
}
}
if (count == 0)
return 0;
return total / count;
2)To check find the max and min value simply loop through the array like this
int min = Integer.MAX_VALUE;
int max = Integer.MIN_VALUE;
for (int i = 0; i < x.length; i++) {
if (x[i] < min)
min = x[i];
if (x[i] > max)
max = x[i];
}
3)To allow the user to modify the array, you could print the values and prompt them as to which value they would like to change like this.
System.out.print("Array: ");
for (int i = 0; i < x.length; i++) {
System.out.print(i + ",");
}
System.out.println();
System.out.println("Which value would you like to change?");
int index = input.nextInt();
System.out.println("What do you want the new value to be?");
int value = input.nextInt();
You can then run a method that changes the value of the array
edit(x, index, value);
public static int edit(int[] n, int index, int value) {
n[index] = value;
return n;
}

I used JS for this task, you can just rewrite my code to Java language.
A number is divisible by 2 if the result of its division by 2 has no
remainder or fractional component - in other terms if the result is an
integer. Zero is an even number because when 0 is divided by
2, the resulting quotient turns out to also be 0 - an integer (as a
whole number that can be written without a remainder, 0 classifies as
an integer).
function compareEvenOddAverage(arr) {
let even = 0,
odd = 0,
evenCounter = 0,
oddCounter = 0,
str = '';
for (let i = 0; i < arr.length; i++) {
if (arr[i] % 2 === 0) {
even += arr[i];
evenCounter++;
} else {
odd += arr[i];
oddCounter++;
}
}
if (even / evenCounter > odd / oddCounter) {
str += 'Average value of even numbers is greater';
} else if (even / evenCounter < odd / oddCounter) {
str += 'Average value of odd numbers is greater';
} else {
str += 'Average values are equal';
}
return str;
}
console.log(compareEvenOddAverage([0, 1, 2, 3, 4, 5]));

There's something wrong in my Magic Square Algorithm

Hi I created a Magic Square program in java
It works fine if you input a number 3 but if i input 5 and so on
there's a problem occurring..
The pattern becomes wrong.
Please help me to find out what's wrong in my code:
Here's my code:
Scanner input = new Scanner(System.in);
System.out.print("Enter a number: ");
int num = input.nextInt();
// Number must be ODD and not less than or equals to one to continue
while ((num % 2 == 0) || (num <= 1)) {
System.out.println("Enter a valid number: ");
num = input.nextInt();
}
int[][] magic = new int[num][num];
int row = 0;
int col = num / 2;
magic[row][col] = 1;
for (int i = 2; i <= num * num; i++) {
if (magic[(row + 5) % num][(col + 2) % num] == 0) {
row = (row + 5) % num;
col = (col + 2) % num;
} else {
row = (row + 1 + num) % num;
}
magic[row][col] = i;
}
for (int x = 0; x < num; x++) {
for (int j = 0; j < num; j++) {
System.out.print(magic[x][j] + "\t");
}
System.out.println();
}
}
It's correct when i Input 3,
here's the output:
But when i type a number like 5:
It becomes:
UPDATED!

You seem to be trying to implement the Method for constructing a magic square of odd order.
The method prescribes starting in the central column of the first row with the number 1.
You seem to have that right.
After that, the fundamental movement for filling the squares is diagonally up and right, one step at a time.
I would code this as:
int newRow = row - 1;
int newCol = col + 1;
When an "up and to the right" move would leave the square, it is wrapped around to the last row or first column, respectively.
This is clearly:
if ( newRow < 0 ) {
newRow = num - 1;
}
if ( newCol > num - 1 ) {
newCol = 0;
}
If a filled square is encountered, one moves vertically down one square instead, then continues as before.
if (magic[newRow][newCol] != 0) {
newRow = row + 1;
newCol = col;
}
I know this doesn't actually solve your problem but I hope it gets you somewhere towards your goal. See how I take the words of the algorithm and match them as accurately as possible with code.