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

Posted on 2003-10-27
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Last Modified: 2011-09-20
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
0
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Question by:crystalfish0318
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10 Comments
 
LVL 15

Accepted Solution

by:
jimmack earned 20 total points
ID: 9626075
See your previous questions for clues about the output.

For the uppercase letters:


        for (char i = 'A'; i <= 'Z'; i++)
        {
            System.out.print(i + " ");
        }
        System.out.println();
0
 

Author Comment

by:crystalfish0318
ID: 9626222
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".......................
0
 
LVL 15

Expert Comment

by:jimmack
ID: 9626243
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++;
           }

0
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Author Comment

by:crystalfish0318
ID: 9626280
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.................
0
 
LVL 15

Expert Comment

by:jimmack
ID: 9626293
That's OK.  Just add the following line before the "while"

firstNum++;
0
 

Author Comment

by:crystalfish0318
ID: 9626310
darn! i should have known this.
thank you so much, jimmack
0
 
LVL 15

Expert Comment

by:jimmack
ID: 9626345
;-)

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;

0
 

Author Comment

by:crystalfish0318
ID: 9626400
/*
 *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?
0
 
LVL 15

Expert Comment

by:jimmack
ID: 9626407
Yes.

Try:

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

(It's a bit more descriptive)
0
 

Author Comment

by:crystalfish0318
ID: 9626411
thank you^^
0

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