asked on

use while loop to output the sum of the square of odd numbers

First, i prompt the user to input 2 integers: firstNum & secondNum (firstNum must be less than secondNum)
this is easy.
then,
i have to output the sum of the square of odd numbers between these two integers,
so i write the codes like this:

import java.io.*;
import java.util.*;
import java.math.*;

public class OddSquare
{
      static BufferedReader keyboard =
                        new BufferedReader(new InputStreamReader(System.in));

      public static void main(String[] args) throws IOException
      {
            double firstNum, secondNum, n, square;

            n = 0;

            System.out.print("please enter an integer: ");
            System.out.flush();
            firstNum = Integer.parseInt(keyboard.readLine());

            System.out.print("please enter another one that is larger than the first integer: ");
            System.out.flush();
            secondNum = Integer.parseInt(keyboard.readLine());

            while(firstNum < secondNum)
            {
                  if(firstNum%2 == 0)
                  {
                        firstNum = firstNum + 2;
                        square = Math.pow(firstNum, 2);
                        System.out.print(square + " ");
                  }
                  else
                  {
                        firstNum = firstNum + (2*n + 1);
                        n++;
                        square = Math.pow(firstNum, 2);
                        System.out.print(square + " ");
                  }
            }
      }
}

i input 3 and 17, then the ouput is unexpected:
"16.0 36.0 64.0 100.0 144.0 196.0 256.0 324.0"

why?
i don't know which part i did wrong?

by the way,
can anyone give me a hint of how to "output all uppercase letters"?

thanks

ASKER CERTIFIED SOLUTION

jimmack

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crystalfish0318

ASKER

import java.io.*;
import java.math.*;
import java.util.*;

public class ch5_num8_partE_SumOfSquareOfOddNumbers
{
      static BufferedReader keyboard =
new BufferedReader(new InputStreamReader(System.in));

public static void main(String[] args) throws IOException
      {
            int firstNum, secondNum, n, sum, rem;

            double result;

            System.out.print("please enter an integer: ");
            System.out.flush();
            firstNum = Integer.parseInt(keyboard.readLine());

            System.out.print("please enter another one that is larger than the first integer: ");
            System.out.flush();
            secondNum = Integer.parseInt(keyboard.readLine());

            rem = firstNum % 2;


             while (++firstNum < secondNum)
             {
                   if (firstNum % 2 != 0)
                   result = Math.pow(firstNum,2);
System.out.println(result + " ");
firstNum++;
             }
      }
}

there's still one error on the "result".......................

jimmack

You're missing some braces and you are incrementing firstNum in two places.

Try the following:

while (firstNum < secondNum)
{
if (firstNum % 2 != 0)
{
result = Math.pow(firstNum,2);
System.out.println(result + " ");
}
firstNum++;
}

crystalfish0318

ASKER

input:
3
17

the output becomes:
9.0
25.0
49.0
.
.
.
.
225.0

the "9.0" shouldn't appear..................
cause 3 isn't between 3 and 17.................

jimmack

That's OK. Just add the following line before the "while"

firstNum++;

crystalfish0318

ASKER

darn! i should have known this.
thank you so much, jimmack

jimmack

;-)

Don't forget, your question wants the "sum" of the squares.

Create another variable:

double squareSum = 0.0;

Then, inside the loop, between "result = " and "System.out...", do

squareSum += result;

crystalfish0318

ASKER

/*
*Filename: ch5_num8_partE_SumOfSquareOfOddNumbers
*Versoon: v1.0
*Description: This program uses a while loop to:
*        1) Prompt the user to input two integers: firstNum and secondNum.
*             2) Output the sum of the square of odd numbers between firstNum
*                         and secondNum.
*Author:        Daniel Yen-Chung Chen
*Created on: October 22, 2003
*/

import java.io.*;
import java.math.*;
import java.util.*;

public class ch5_num8_partE_SumOfSquareOfOddNumbers
{
      static BufferedReader keyboard =
new BufferedReader(new InputStreamReader(System.in));

public static void main(String[] args) throws IOException
      {
            int firstNum, secondNum, n, sum, rem;

            double result;

            double squareSum = 0.0;


            System.out.print("please enter an integer: ");
            System.out.flush();
            firstNum = Integer.parseInt(keyboard.readLine());

            System.out.print("please enter another one that is larger than the first integer: ");
            System.out.flush();
            secondNum = Integer.parseInt(keyboard.readLine());

            rem = firstNum % 2;

            firstNum++;

            while (firstNum < secondNum)
{
      if (firstNum % 2 != 0)
      {
            result = Math.pow(firstNum,2);
            squareSum += result;
            System.out.println(result + " ");
}

firstNum++;
}

      }
}

............
now the output is:
25.0
49.0
81.0
121.0
169.0
225.0
shouldn't i add the "System.out.println(squareSum);" after the while loop?

jimmack

Yes.

Try:

System.out.println("Sum of squares = " + squareSum);

(It's a bit more descriptive)

crystalfish0318

ASKER

thank you^^