first java program is not working

Question

I'm new in Java, it's my first attempt to write a program: I need to write a program that prints the sum of all positive integers smaller than 1000, that are divided by either 3 or 5. Here is my (poorly) attempt. after compiling it is just receiving numbers and showing them :

import java.util.Scanner;
public class ex1 {
    public static void main(String[] args) {
        int num=1;
        int count = 1;
        while (count <=1000) {
            if (count%3==0|count%5==0){
                count = count+num;
                count++;
            }
        }
        System.out.println(count);
    }
}

count = count+num; kind of seems wrong for what count "seems" to be used for — MadProgrammer
– MadProgrammer, Commented Mar 17, 2015 at 11:50
You seem to be using count for two purposes - this won't work. You first line should be num += count. — Boris the Spider
– Boris the Spider, Commented Mar 17, 2015 at 11:50
"first java program is not working" - Congratulations, you have your first bug! :-) — Stephen C
– Stephen C, Commented Mar 17, 2015 at 11:56

Diego Martinoia · Accepted Answer · 2015-03-17 11:56:26Z

3

Given you used a while, I assume you don't know about for loops, so I'll avoid using it.

Your code should:

Your initial sum, before any number, is 0
Iterate (i.e. go through the values) the values from 1 to 1000
If the value is divisible by 3 or 5, add it to a sum.
Print the sum.

Point 1):

int sum = 0;

Point 2):

int value = 1;
while (value <= 1000) {
   //do point 3
   value++;
}

Point 3):

if ((value%3==0) || (value%5==0)) {
  sum = sum + value;
}

Point 4):

System.out.println(sum);

Putting it all together:

int sum = 0;
int value = 1;
while (value <= 1000) {
  if ((value%3==0) || (value%5==0)) {
    sum = sum + value;
  }
  value++;
}
System.out.println(sum);

Your main error is in using count both for the sum and for the value check of the while condition. The misusage of the single pipe as or is also a mistake.

Hope this helps

answered Mar 17, 2015 at 11:56

Diego Martinoia

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1 Comment

Stephen C Over a year ago

In fact, the use of | instead of || makes no practical difference here. It is at worse a "stylistic mistake".

Mahesh · Accepted Answer · 2015-03-17 11:55:25Z

1

public class Test {

      public static void main(String[] args) {
            int num=1;
            int sum=0;
            while (num <=1000) {
                if (num%3==0||num%5==0){
                    sum = sum +num;
                }
                num++;
            }
            System.out.println(sum);
        }
    }

answered Mar 17, 2015 at 11:55

Mahesh

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1 Comment

Stephen C Over a year ago

Yea great. How about explaining what the problem was? In words?

Razib · Accepted Answer · 2015-03-17 11:59:38Z

0

You have put your count++ inside if block. That means if the number is divisible by 3 or 5 then you are incrementing the count . Place it outside of your if block. I have re-write your code as follows -

import java.util.Scanner;

public class ex1 {
    public static void main(String[] args) {

        int sum = 0;
        int count = 1;

        while (count <=1000) {
            if (count%3==0||count%5==0){
                sum = sum + count;
            }
            count++;

        }
        System.out.println(sum);
    }
}

answered Mar 17, 2015 at 11:59

Razib

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