binary search error

[joey shertz]

How do I make it so I am able to enter any number rather then just the numbers in the arrays? I want it to be able to find the position of any number between 0-100
BTW I am Joe and this is my first post.

import javax.swing.*;
public class BinarySearch {
 public static void main(String[] args) {
  int array[] = new int[11];
  array[0] = 10;
  array[1] = 20;
  array[2] = 30;
  array[3] = 40;
  array[4] = 50;
  array[5] = 60;
  array[6] = 70;
  array[7] = 80;
  array[8] = 90;
  array[9] = 100;
  array[10] = 110;
  int size = array.length;
  int low = 0;
  int mid = low+size/2;
  int num=0;
  System.out.println("The current array contains following data: ");
  for(int i = 0 ; i<=10 ; i++)
  {
   System.out.print(array[i]+"\t");
  }
  System.out.println();
  String input_box = JOptionPane.showInputDialog("Enter the element to be searched: ");
  try 
  {
  num = Integer.parseInt(input_box);
  if(num>array[size-1] || num < array[0]) 
  {
   System.out.println("Number doesn't exist.");
  }
  else{
  while(array[(low+size)/2]!= num){
   if(num>array[(low+size)/2])
   {
    System.out.println("Setting low to "+mid);
    low = mid;
    mid=(mid+size)/2;
   }
   else{

    System.out.println("Setting size to "+mid);
    size = mid;
    mid=mid/2;
    }  
  }//Close while loop
  System.out.println("The number is at position: "+(low+size)/2);
  }//End main if
  }//End try
  catch(Exception e)
  {
   JOptionPane.showMessageDialog(null, "Error:\n You need to enter a number,not string", "Invalid Number!", JOptionPane.WARNING_MESSAGE);
  }
 }}

[Moderator edit: added code tags]

[Junilu Lacar]

Hi Joe,

Welcome to the Ranch!

If you're going to post code, please UseCodeTags (←click on the link to learn how to do that). Also, you should try to format your code properly to make it easier for other people to read it. I find the Google Java Style Guide a good reference. There's also the JavaRanch Style Guide.

[joey shertz]

Thanks, will use the code tag from now on.

[Junilu Lacar]

I don't really understand what you want. Can you give a concrete example to clarify?

[joey shertz]

The only positions the code finds are the arrays listed, ie 10,20,30,40,50, etc. I want to find a way to be able to find the position of any number. ( like 44, 56 etc )

[Junilu Lacar]

joey shertz wrote:The only positions the code finds are the arrays listed, ie 10,20,30,40,50, etc. I want to find a way to be able to find the position of any number. ( like 44, 56 etc )

How do you expect to find something that's not in your array?

Lines 5-15 of your code listing determine which values you will be able to find. How can you expect to find numbers like 44 and 56 if you don't put them there?

[joey shertz]

Ok I worded it wrong. Is there a way to add all my 1-100 numbers w/o adding 100 arrays?

[Junilu Lacar]

joey shertz wrote:Ok I worded it wrong. Is there a way to add all my 1-100 numbers w/o adding 100 arrays?

"You keep using that word. I don't think it means what you think it means" - Inigo Montoya in "The Princess Bride"

You only have one array. You mean to say elements of the array.

Since you have already learned about the for-loop, can you think of a way you can use one to assign increasing values to each successive element of your array? That is, you first declare an array of 100 integers (instead of the 11 that you're declaring now). Then you use a loop to set the value of each of those elements to a number that's bigger than the previous one, if there is any. The only case where there is no previous element is, of course, for the very first element (index = 0).

You need to assign increasing values to your array elements because that's the only way a binary search will work.

[Campbell Ritchie]

Otherwise you would have to [copy your array with the clone method and] sort it before you can try binary search.