Skip to main content

Binary Search: A Method of Searching

Binary Search method is popular for searching a specific item in an ordered array (sorted). It can perform the search in minimum possible comparisons, but it needs the array to be sorted in any order.

Practically, it is used when the data is itself sorted initially or needs to be sorted for other activities also. This is because you don’t want to first sort the data and then use binary search, in that case use of linear search would be practical.

Binary Search Algorithm

Suppose,

  • The array to be AR[SIZE] having SIZE number of elements.

  • L is the index number of the lower element. We take it to be 0.

  • U is the index number of the upper (last) element. It will be (SIZE-1).

  • ITEM is the data that needs to be searched.

  • beg, last and mid are variables of type int(eger).

Here is the algorithm:

  1. LET beg = L AND last = U
  2. REPEAT STEPS 3 THROUGH 6 TILL beg<=last
  3. mid = ( (beg+last)/2)
  4. IF AR[mid] = ITEM THEN
           ITEM IS AT POSITION mid
           BREAK THE LOOP
  5. IF AR[mid] < ITEM THEN
           beg = mid+1
  6. IF AR[mid] > ITEM
           last = mid-1
  7. END OF LOOP
  8. IF AR[mid] = ITEM THEN
           SEARCH IS UNSUCCESSFULL

Here is the example program:

  // BINARY SEARCH PROGRAM
  // example program in C++

  #include<iostream.h>

  void main(void)
  {
   int beg, last, mid, item, i;
   int ar[5];

   // sorted data needs to be input
   cout<<"enter sorted data:\n";
   for(i=0; i<5; i++)
     cin>>ar[i];

   cout<<"enter search term:";
   cin>>item;

   // as per array
   beg=0;
   last=5;

   // binary searching starts
   while(beg<=last)
     {
      // calculate the middle
      // of the array section
      mid=((beg+last)/2);

      if (ar[mid]==item)
        {
         cout<<"\n\n";
         cout<<item<<" found at index no. "<<mid;
         break;
        }

      if(ar[mid]<item)
        beg=mid+1;// should be beg=mid-1 for
        // data in descending order

      if(ar[mid]>item)
        last=mid-1;// should be beg=mid+1 for
        // data in descending order
     }
     // search end

   if(!(ar[mid]==item))
     cout<<"\nSearch unsuccessfull!";

   cout<<endl;
  }

Good-Bye guys!

Do check back for updates!

Related Articles:

Popular posts from this blog

Fix For Toshiba Satellite "RTC Battery is Low" Error (with Pictures)

RTC Battery is Low Error on a Toshiba Satellite laptop "RTC Battery is Low..." An error message flashing while you try to boot your laptop is enough to panic many people. But worry not! "RTC Battery" stands for Real-Time Clock battery which almost all laptops and PCs have on their motherboard to power the clock and sometimes to also keep the CMOS settings from getting erased while the system is switched off.  It is not uncommon for these batteries to last for years before requiring a replacement as the clock consumes very less power. And contrary to what some people tell you - they are not rechargeable or getting charged while your computer or laptop is running. In this article, we'll learn everything about RTC batteries and how to fix the error on your Toshiba Satellite laptop. What is an RTC Battery? RTC or CMOS batteries are small coin-shaped lithium batteries with a 3-volts output. Most laptops use

The Best Way(s) to Comment out PHP/HTML Code

PHP supports various styles of comments. Please check the following example: <?php // Single line comment code (); # Single line Comment code2 (); /* Multi Line comment code(); The code inside doesn't run */ // /* This doesn NOT start a multi-line comment block /* Multi line comment block The following line still ends the multi-line comment block //*/ The " # " comment style, though, is rarely used. Do note, in the example, that anything (even a multi-block comment /* ) after a " // " or " # " is a comment, and /* */ around any single-line comment overrides it. This information will come in handy when we learn about some neat tricks next. Comment out PHP Code Blocks Check the following code <?php //* Toggle line if ( 1 ) {      // } else {      // } //*/ //* Toggle line if ( 2 ) {      // } else {      // } //*/ Now see how easy it is to toggle a part of PHP code by just removing or adding a single " / " from th

Designing a Simple Order Form Application in PHP

Ok guys, for this post we’re going to create a simple yet complete order form page. Order forms are used on many sites to take customers order online. Order forms should have the capability to take orders from visitors regarding what items they want to purchase and store the information for further processing. For this post’s example, we are going to create an order form for a Book Seller. The form will be designed to take order of five different items (books). Our order form application should be able to take order of five different items in any separate quantities tht user wants, it should also ask for shipping address and name of the customer. It should then store the information provided in a file along with the date and time order was placed. The application should also be able to take any number of orders and store them all linearly for further human processing. For this, we need a front end of a HTML form to which the user would interact a