I am currently trying to find out the sum of digits in a number. However, I am experiencing problems when I display the sum as it still shows all the previous sums, not just the final sum of digits only that I want.
int rem = 0, sum = 0, input = 0;
Scanner k = new Scanner(System.in);
System.out.println("Enter a number");
input = k.nextInt();
while (input > 0){
rem = input % 10;
sum = sum + rem;
input = input / 10;
System.out.println(sum);
}
This is part of my program above. So for example, when I input the number 25, the program outputs the number 5 first then 7. I understand why it inputs the number 5 as it is the remainder when divided by 10 and since I initialised sum = 0 at the start, the first sum will come out as 5 since sum = 0 + 5. However, I only want the final digit sum to be displayed.
How should I approach this problem?
Any tips and advice would be greatly appreciated.
The while loop is the thing that compute the sum, so you need to print the result after the computing :
while (input > 0){
rem = input % 10;
sum = sum + rem; //same as : sum += rem
input = input / 10; //same as : input /= 10;
}
System.out.println(sum);
Next to that, whith some tricks, and remove rem variable, this is equivalent :
while (input > 0) {
sum += input % 10; //sum +=rem; --> sum += (input%10);
input /= 10;
}
System.out.println(sum);
Just print the result of the summation after the while loop. You find the every summation result of the number is because you print the result in your while loop.
You should do as follows:
while (input > 0){
rem = input % 10;
sum = sum + rem;
input = input / 10;
}
System.out.println(sum);
if your input is 25, then it will show the summation as 7.
As others said, the issue is that you print out the value of the sum variable inside your while loop.
Either you change your code to:
while (input > 0) {
sum += input % 10;
input /= 10;
}
System.out.println(sum);
or you can use streams:
public static void main(String[] args) {
//1. Step: Read the number
Scanner scanner = new Scanner(System.in);
System.out.println("Enter a number");
Integer input = scanner.nextInt();
scanner.close();
//2. Step: calculate the sum with streams
int sum = String.valueOf(input).chars().map(Character::getNumericValue).sum();
//3. Step: Print out the result
System.out.println(sum);
}
Essentially what happens in the second step is this:
We convert the integer into a string, we get the characters of the string and we call for each character using the map call the getNumericValue method to convert the character back to an integer, then we call the sum method to calculate the sum of these integers.
Related
public class Hello {
public static void main(String [] args){
int number, count = 0, sum = 0;
int Largest= 0, largestEvenNumber = 0;
Scanner console = new Scanner(System.in);
number = console.nextInt(); // read an integer entered by a user
if (number > Largest) { // Condition for computing the largest number
Largest = number;
}
if (number < 0) { // Condition for computing the number of negative integers in the sequence
count = count + 1;
}
if (number % 2 == 0) { // Condition for computing the largest even integer in the sequence
if (largestEvenNumber < number) {
largestEvenNumber = number;
}
}
if (number % 3 == 0) { // Condition for computing the sum of numbers divisible by 3
sum += number;
}
System.out.println("\nThe largest integer is " + Largest);
System.out.println("The number of negative integers in the sequence is " + count);
System.out.println("The largest even integer in the sequence is " + largestEvenNumber);
System.out.printf("The sum of numbers divisible by 3 is %d", sum);
}
}
I would like to get the expected output given below. But, the Scanner class is reading only the first number. How do I correct this without creating multiple objects?
Output:
2
-1
-5
-3
9
8
0
The largest integer is 2
The number of negative integers in the sequence is 0
The largest even integer in the sequence is 2
The sum of numbers divisible by 3 is 0
Process finished with exit code 0
expected Output:
The largest integer is 9
The number of negative integers in the sequence is 3
The largest even integer in the sequence is 8
The sum of numbers divisible by 3 is 6
Thank you!
You only call console.nextInt() once, so only one number is read. If you want to call you need to loop over calls to console.hasNext(). Since you're using System.in. E.g.:
while (console.hasNextInt()) {
number = console.nextInt();
// calculations
}
You are only reading input once. I don't see a loop in your code, so number = console.nextInt(); only runs once. What you should do is put it inside a loop, exit the loop when you have all the numbers (how you check that can be done in multiple ways), and while you're inside the loop put whatever input you receive into an array or another data structure. After you're done collecting input, do your checks over all the numbers on your data structure.
1- You must first receive the data from the user and then calculate it and generate the output. You can do this using the arrays and after finishing put your data, calculate on them.
for example :
private static final int DATA_SIZE = 5;
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
ArrayList<Integer> data = new ArrayList<>();
// put data in array
while (data.size() == DATA_SIZE){
data.add(scanner.nextInt());
}
// calculate data from array ...
}
2- When you call a field like nextInt() Scanner class , it is done only once, then you put it in a loop to be repeated several times ...
Of course, I have other suggestions for doing this
For example, you can use the array available in the main method (with knowledge, of course)
OR
First ask the user for the amount of data you have, then take it and then calculate
OR....
If you want to type all number at once ,you should set a terminal number. when you input all you number,you shoud add the terminal number to indicate input is over.
For example:
public static void main(String [] args){
int number, count = 0, sum = 0;
int Largest= 0, largestEvenNumber = 0;
Scanner console = new Scanner(System.in);
int endNumber = -1; //set the terminal number
do {
number = console.nextInt(); // read an integer entered by a user
if (number > Largest) { // Condition for computing the largest number
Largest = number;
}
if (number < 0) { // Condition for computing the number of negative integers in the sequence
count = count + 1;
}
if (number % 2 == 0) { // Condition for computing the largest even integer in the sequence
if (largestEvenNumber < number) {
largestEvenNumber = number;
}
}
if (number % 3 == 0) { // Condition for computing the sum of numbers divisible by 3
sum += number;
}
}while (number!=endNumber);
System.out.println("\nThe largest integer is " + Largest);
System.out.println("The number of negative integers in the sequence is " + count);
System.out.println("The largest even integer in the sequence is " + largestEvenNumber);
System.out.printf("The sum of numbers divisible by 3 is %d", sum);
}
The line if code is only being executed once. Thus, the Scanner is only taking in the first in put. Use a while loop to take in multiple inputs.
I am very new to coding and Java. I have the following assignment: Write a program that reads a couple of positive numbers from the input and computes and prints the average, with 3 decimals precision. The input list closes with the number -1.
So I have a working program, however I have no clue how to integrate the condition 'print the average with 3 decimals precision'. Do you have any idea how to fix this? Many thanks!
See my code below:
import java.util.Scanner;
public class Parta {
public static void main(String[] args){
Scanner numInput = new Scanner(System.in);
double avg = 0.0;
double count = 0.0;
double sum = 0.0;
System.out.println("Enter a series of numbers. Enter -1 to quit.");
while (numInput.hasNextDouble())
{
double negNum = numInput.nextDouble();
if (negNum == -1)
{
System.out.println("You entered " + count + " numbers averaging " + avg + ".");
break;
}
else
{
sum += negNum;
count++;
avg = sum/count;
}
}
}
}
You just have to break out of the loop for your -1 condition.
while(1) {
Scanner sc = new Scanner(System.in);
int n = sc.nextInt();
if(n == -1)
break;
}
Change
for(int i=0; i < numbers.length + 1= -1 ; i++)
to
for(int i=0; i < n ; i++)
The
%n
is out of place in the print statement also. I'd remove that.
To implement your -1 condition, check for a == -1 in the for loop:
if (a == -1) {break;}
The input list closes with the number -1.
I assume this means that -1 is the final number you are looking for and when read then all inputs are then completed? You just need a condition to check if the number you are looking at is -1, if it is then stop reading.
Your code does not meet your requirements.
The first requirement is that you have to calculate fractions. But you stick to int as type of your variables. As written by #nbokmans your variables should be of type double or float.
The other problem is that your code takes the first number given as the count of the numbers to follow. But you're told to use any number for calculation until input is -1. You cannot do this with a for loop, you need a while loop for this.
An the easiest way to accomplish your task is to calculate the result on the fly while getting the input:
pseudo code:
declare sum as double initially 0.0;
while(input is not -1)
sum = (sum + input) / 2;
output sum:
import java.util.Scanner;
public class OddSum {
public static void main(String[] args) {
int num;
int i = 1;
int sum = 0;
Scanner input = new Scanner(System.in);
System.out.print("Enter a number: ");
num = input.nextInt();
input.close();
while (i<=num) {
i += 2;
sum +=i;
}
System.out.println("The sum of odd numbers between 1 and" + num + "is: " + sum);
}
}
I wrote this code to sum up the odd numbers from 1 to a number entered.
Now, when I entered 8, I got the output as 24, against the desired output 16.
Can you tell me what went wrong?
You are incrementing the variable before performing summation .
while (i<=num) {
sum +=i;
i += 2;
}
You should add i to sum before adding to 2 to i. Thus, once i goes past num, the while loop will no longer execute.
import java.util.Scanner;
public class OddSum {
public static void main(String[] args) {
int num;
int i = 1;
int sum = 0;
Scanner input = new Scanner(System.in);
System.out.print("Enter a number: ");
num = input.nextInt();
input.close();
while (i<=num) {
// add i to sum before adding 2 to i
sum += i;
i += 2;
}
System.out.println("The sum of odd numbers between 1 and" + num + "is: " + sum);
}
Lets debug the code together:
after taking the number it would go to i<=num that while condition. Great, Then instead of getting sum it would + again 2 which cause 3. So what's happen? First case, 1 is not added before and first iteration value 1 is lose. That means whenever, you enter the loop. It goes increases before adding the previous value. So, rewrite the code this way:
while (i<=num) {
sum +=i;
i += 2;
}
You may use for instead:
for(int i=1;i<=num;i+=2){
sum +=i;
}
You're incrementing i before you sum it, instead of afterwards:
while (i <= num) {
sum +=i;
i += 2;
}
It's worth noting, though, that these kind of issues, where the loop variable is incremented by a constant, are often more convenient to write with a for loop:
for (int i = 1; i <= num; i += 2) {
sum += i;
}
Or better yet, if you're using Java 8, by collecting a stream:
int sum = IntStream.rangeClosed(1, num).filter(i -> i % 2 != 0).sum();
The reason why the result for your example with N = 8 gives 24 is because when i reaches value 7, the loop is continued and is added the value 9 to your sum too and you forget to add the first odd number: 1, because you start over from adding directly 3 to your sum.
You can either switch the statements between each other, either use a for loop instead of while:
for(int i = 1; i <= num; i += 2) {
sum += i;
}
Working on a project where the user input determines the size of an array. Afterwards the user inputs values and receives the sum. Finally the program shows the user the percentage of each value to the total. For example if the array size is 4 and a[0] = 2, a[1] = 1, a[2] = 1, and a[3] = 2 it will show "2, which is 33.333% of the sum" "1, which is 16.666% of the sum" etc. The problem I have is that after the array and sum are determined and I try to find the percentage I get 0. Is the sum reset to 0 since it's a different for loop?
import java.util.Scanner;
public class CountIntegersPerLine
{
public static void main(String[] args)
{
int elements;
int arraySize;
int sum = 0;
int percentage;
System.out.println("How many numbers will you enter?");
Scanner keyboard = new Scanner(System.in);
//Length of array is determined by user input
arraySize = keyboard.nextInt();
int[] array = new int[arraySize];
System.out.println("Enter 4 integers, one per line");
for (elements = 0; elements < arraySize; elements++)
{
//Gather user input for elements and add the total value with each iteration
array[elements] = keyboard.nextInt();
sum = sum + array[elements];
}
System.out.println("The sum is " + sum);
System.out.println("The numbers are:");
for (elements = 0; elements < arraySize; elements++)
{
//Display the percent that each value contributes to the total
percentage = array[elements] / sum;
System.out.println(array[elements] + ", which is " + percentage + " of the sum.");
}
System.out.println();
}
}
Integer division will result in a zero value when the numerator is less than the denominator. You should declare percentage as a float or a double.
int percentage;
...
...
...
percentage = array[elements] / sum;
and you will need to cast the division operation in your case to preserve the value:
percentage = (double)array[elements] / sum;
Try declaring the sum variable as a double (or float):
double sum = 0.0;
Why? because in this line:
percentage = array[elements] / sum;
... You're performing a division between two integers, and all the decimals will be lost. You can verify that this is indeed the case, for example try this:
System.out.println(1/3); // it'll print 0 on the console
The solution to this problem is to have either one of the division's operands as a decimal number, by declaring as such their types (as I did above) or by performing a cast. Alternatively, this would work without changing sum's type:
percentage = array[elements] / ((double)sum);
I am trying to write a simple and quite useless program to generate a list of all integers 1><1000 where the sum of digits is 11. Every time I run this, I end up in an infinite loop. I've tried different things - for(){}, while(){}, adding a if(count>500){break;} to halt it after the loop counter reaches 500....still nothing...where am I going wrong in this?
Thanks in advance
//loops through all numbers whose sum of digits is 11
for(int number = 29; number < 1000; number++) {
//checks the values of the 100,10,and 1 position
int hPlace = number / 100; number = number - (hPlace * 100);
int tPlace = number / 10; number = number - (tPlace * 10);
int oPlace = number;
//sum of digits
int i = hPlace + tPlace + oPlace;
//prints if sum of digits is 11
int count = 0;
if (i == 11) {
count++;
System.out.print(i + " ");
}
//new line after every 10 numbers -- just for formatting
if (count % 10 == 0) {
System.out.println("");
}
}
You are using same variable as controller for your fors. Try to change the controller variable within the for structure from number to number1
You are changing the variable here:
---------------------------------
int hPlace = number / 100; number = number - (hPlace * 100);
---------------------------------
Don't do this
number = number - (hPlace * 100);
when your condition is dependent on number
for(int number = 29; number < 1000; number++)
because you have two nested for loops which both of them use the same variable as counter
for(int number = 29; number < 1000; number++) {
for(number = 29;number < 930;number++) {
//loops through all numbers whose sum of digits is 11
for(int number = 29; number < 1000; number++) {
//checks the values of the 100,10,and 1 position
int hPlace = number / 100;
**number** = number - (hPlace * 100); // PROBLEM!!!
int tPlace = number / 10;
**number** = number - (tPlace * 10); // PROBLEM!!!
int oPlace = number;
//sum of digits
int i = hPlace + tPlace + oPlace;
//prints if sum of digits is 11
int count = 0;
if (i == 11) {
count++;
System.out.print(i + " ");
}
//new line after every 10 numbers -- just for formatting
if (count % 10 == 0) {
System.out.println("");
}
}
if(count>500){break;} to halt it after the loop counter reaches 500....still nothing
This won't work because you're redeclaring count with an initial value of 0 everytime. So the if will always return false.
Also, these following lines:
int hPlace = number / 100; number = number - (hPlace * 100);
int tPlace = number / 10; number = number - (tPlace * 10);
Modify number, which is your loop variable. Your loop will not perform correctly if you modify the loop variable in unexpected ways. Instead, copy the value over to another variable.
Don't change the value of you loop control variable inside the loop, or dangerous things may result. Instead, copy the value into a new variable and use that in the loop.
import java.io.BufferedReader;
import java.io.InputStreamReader;
public class SumDigits
{
public static void main(String args[])throws Exception
{
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
System.out.print("Enter a Number:");
String string=br.readLine();
System.out.println("length of Number:"+string.length());
int sum=0;
int number=0;
for(int i=0;i<=string.length()-1;++i)
{
char character=string.charAt(i);
number=Character.getNumericValue(character);
sum=sum+number;
}//for
System.out.println("Sum of digits of Entered Number:"+sum);
}//main()
}//class