I was wondering how to load up an array (with user input) using a while loop. The code below prints a 0.
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
int i = 0;
int n = 0;
int[] myArray = new int[10];
System.out.printf("enter a value>>");
while (scan.nextInt() > 0) {
for (i = 0; i > 0; i++) {
myArray[i] = scan.nextInt();
}
System.out.printf("enter a value>>");
}
System.out.printf("array index 2 is %d", myArray[2]);
}
There are multiple things wrong with your code:
First of all
while(scan.nextInt() > 0){
Scanner.nextInt() returns an int from your standard input so you actually have to pick up that value. You are checking here what the user typed but then not using it at all and storing the next thing that the user types by saying:
myArray[i] = scan.nextInt();
You don't really need the outer while loop, just use the for loop, its enough.
However, your for loop is off as well:
for(i = 0; i > 0; i++){
It starts at i equal to 0 and runs while i is greater than 0. This means it will never actually run the code within the loop because 0 is never greater than 0. And if it did run (you started it at some number < 0), you would end up in an infinite loop because your condition i > 0 is always true for positive numbers.
Change the loop to:
for(i = 0; i < 10; i++){
Now, your loop could look like:
for(i = 0; i < 10; i++){ // do this 10 times
System.out.printf("enter a value>>"); // print a statement to the screen
myArray[i] = scan.nextInt(); // read an integer from the user and store it into the array
}
one other way to do it
Scanner scan = new Scanner(System.in);
List list = new ArrayList();
while(true){
System.out.println("Enter a value to store in list");
list.add(scan.nextInt());
System.out.println("Enter more value y to continue or enter n to exit");
Scanner s = new Scanner(System.in);
String ans = s.nextLine();
if(ans.equals("n"))
break;
}
System.out.println(list);
public static void main(String[] args)
{
Scanner input =new Scanner(System.in);
int[] arr=new int[4];
int i;
for(i=0;i<4;i++)
{
System.out.println("Enter the number: ");
arr[i]=input.nextInt();
}
for(i=0;i<4;i++)
{
System.out.println(arr[i]);
}
}
Hope this code helps.
Related
My school homework is to declare array with 100 variables.
The actual task is: Declare array with 100 variables. Use do.. while loop to read the data to array. Reading data should be finished when array will be full or when user will enter a negative number.
So far I got:
public static void runTask1() {
Scanner read = new Scanner(System.in);
int[] tab = new int [100];
for (int i = 0; i < tab.length; i++);
System.out.println("Enter number for array ");
tab [] = read.nextInt();
Please help. I'm a total newbie in programming.
You should do your homework yourself ;)
Scanner read = new Scanner(System.in);
int[] tab = new int [100];
int idx=0;
do{
System.out.println("Number for array idx "+idx);
try{
tab[idx] = read.nextInt();
}catch(Exception e){
System.out.println("Wrong input");
}
if(tab[idx]<0) break;
idx++;
}while(idx<100)
Not compiled, just wrote it here.
Try that
public static void main(String[] args) {
Scanner read = new Scanner(System.in);
int[] tab = new int [100];
int index = 0;
while(index < tab.length){
System.out.println("Enter number for array ");
tab[index]= read.nextInt();
if(tab[index]<1) break;
index++;
}
System.out.println(Arrays.toString(tab));
}
I'm working on a question and I'm new to programming, so I'm not that familiar with a few concepts. The question asks the user to input an initial number, followed by a list of that many numbers. The program should then print back how many of the numbers entered were negative.
For example, I first input 5, followed by 5 other random numbers.
5
6,-9,28,-32,-1
The output should be
3
So far all I have is:
class main
{
public static void main(String args[])
{
Scanner scan = new Scanner(System.in);
int input = scan.nextInt();
int c=0;
for(int i = 1; i <= input; i++)
{
System.out.println(i);
if(i<0)
{
c++;
}
}
System.out.println(c);
}
}
I'm really confused. Can someone offer an explanation as to how the code works?
You can read the positive integers inside for loop from the given inputs and then check if that each input integer is greater than or equal to zero:
scanner scan = new Scanner(System.in);
int input = scan.nextInt();
int c=0;
for(int i = 1; i <= input; i++) {
int num = scan.nextInt();
if(num>=0)
{
System.out.println(num);
}
}
import java.util.Scanner;
public class Tar0 {
static Scanner in = new Scanner (System.in);
public static void main(String[] args) {
int d, i = 0, a = 0, f = 1;
System.out.println("Enter How many Digits you want?");
d = in.nextInt();
int num[] = new int[d];
for(i = 0; i < d; i++) {
System.out.println("Enter Single Digit");
num[i] = in.nextInt();
}
for(i = d; i > 0; i--) {
a = a + (num[i] * f);
f = f * 10;
}
System.out.println("The Number is: " + a);
}
}
Question: User will enter number of digits and the program will make from it a number I have wrote the code by myself but it doesnt seems to work.
When Running the program:
the input seems to work fine. I have tried to test the output of the
array without the second loop with the calculation, seems to work
but with the calculation seems to crush:
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 4
at tar0.main(tar0.java:17)
What's the deal?
Java arrays start at 0 and continue up from there. The way your code is formatted right now you are losing a value and therefore your array is too small to hold the values.
One option as outlined above would be to decrement your d value so that we are using a proper array size in the loop. This would be the preferred way so I removed the additional code above for the other option.
import java.util.Scanner;
public class tar0 {
static Scanner in = new Scanner (System.in);
public static void main(String[] args)
{
int d,i=0,a=0,f=1;
System.out.println("Enter How many Digits you want?");
d=in.nextInt();
int num[] = new int[d];
for(i=0;i<d;i++)
{
System.out.println("Enter Single Digit");
num[i]=in.nextInt();
}
for(i = d - 1; i >0 ; i--)
{
a=a+(num[i]*f);
f=f*10;
}
System.out.println("The Number is: "+a);
}
If you have modified the following code it will work.
for(i=d;i>0;i--)
{
a=a+(num[i-1]*f);
f=f*10;
}
Array index value will start at 0. so change array from num[i] to num[i-1]
I'm new with java and i have to write a code that asks the user two numbers an interval. Then the user must introduce n numbers and the program must return how many numbers belong to that interval.
I've tried to do this and this is what i have:
import java.util.*;
public class NumsInter {
public static void main(String[] args) {
Scanner sc;
int a,b,nums,count;
sc = new Scanner (System.in);
System.out.print ("Write two numbers a and b(a<=b)(interval): ");
a=sc.nextInt();
b=sc.nextInt();
count=0;
System.out.println("write a number: ");
while(sc.hasNextInt()){
nums=sc.nextInt();
if (a<=nums && nums>=b){
count= count + 1;
} else {
count= count;
}
}
System.out.println(count +" numbers are included in ("+a+","+b+")");
}
}
Example: If the user writes 2 and 6, and then 4,4,3,1 the output should be 3.
As I am a newbie i don't know how can i do this the good way, can someoen help?
PD: How can i break the loop so i can get the output?
Thank You!
Try something like this
ArrayList<Integer> numbers = new ArrayList<Integer>();
System.out.println("Enter the numbers you want to test, enter 'stop' to stop");
boolean userInput = true;
while(input.hasNextInt() && userInput){
if(input.hasNext("stop")){userInput = false;}
numbers.add(input.nextInt());
}
Where you have a loop that checks if there is a next int while at the same time checking to see if the user is done or not.
And them something like this to print your answer
for(int i =0; i < numbers.size(); i++){
testNum = numbers.get(i);
if(testNum > lowerLimit && testNum < upperLimit){
count++;
}
}
System.out.println(count + " valid numbers have been entered!");
take an int [] no_between_max&min after take the input from user and store in this array. after that take a for loop and compare the value of array with max and min ant increase the count variable.
int noOfItem=sc.nextInt();
int [] no_between_max_min = new int[noOfItem];
for(int i=0;i<noOfItem;i++){
no_between_max_min[i]=sc.nextInt();
}
for(int i=0;i<no_between_max_min.length;i++){
if(no_between_max_min[i]>=a&&no_between_max_min[i]<=b){
count++;
}
}
So i have the following chuckj of code and what i want it do is for the user to enter 5 numbers in the netbeans console.The way i want to do it is he either can enter some by being separting the numbers with a space or line by line for exmaple like the following
But what i want is to "Enter a string of numbers" to be only visiable when it is needed to, for example when he needs to enter the next number. Is it possible to do this?
The following is done by the following code
Scanner reader = new Scanner(System.in);
int number;
List<Integer> numbers = new ArrayList<>();
for (int i = 0; i < 5; i++) {
System.out.println("Enter a string of numbers");
number = reader.nextInt();
numbers.add(number);
}
System.out.println("size" + numbers.size());
for(int takenNumber : numbers){
System.out.println(takenNumber);
}
You could do something like this:
Scanner reader = new Scanner(System.in);
List<Integer> numbers = new ArrayList<>();
int numbersEntered = 0; // Stores how many numbers the user has entered so far
while (numbersEntered < 5) { // Keep asking if they have not entered 5 numbers yet
System.out.println("Enter a string of numbers");
String[] input = reader.nextLine().split(" "); // Split the input by spaces into an array
numbersEntered += input.length; // Add the number of numbers they entered to the variable
for (int i = 0; i < input.length; i++) {
if (numbers.size() < 5) { // Only add the numbers if the list is not full
numbers.add(Integer.parseInt(input[i])); // Add each number they entered to the numbers list
}
}
}
You can use the hasNext() function of Scanner to keep reading while there is more input without doing another prompt. Try:
Scanner reader = new Scanner(System.in);
int number;
ArrayList<Integer> numbers = new ArrayList<Integer>();
int i = 0;
while((i < 5))
{
System.out.println("Enter a string of numbers:");
if(reader.hasNextLine())
{
String[] numbersRead = reader.nextLine().split("\\s");
System.out.print("Read:");
for(int n = 0; n < numbersRead.length; n++)
{
numbers.add(Integer.parseInt(numbersRead[n]));
i++;
}
System.out.println();
}
}