Binary search is simple and fast search algorithm which works on the principle of divide and conquer.

It will work properly when the data collected is in sorted form.

It is having run-time complexity of (log n).

This searching algorithm search a item by comparing the middle item of the given list.

If matches occurs then index of item is returned.

If middle item is greater than item then item is searched in sub-array to the right of the middle item other wise item is search in sub-array to the left of the middle item.

This process will be continued on sub-array as well until the size of subarray reduces to zero.

Use the given two formulas

i.)To determine the half of the array

mid = low + (high - low) / 2

ii.) To find the new mid value again.

low = mid + 1
mid = low + (high - low) / 2

Pseudocode:-

Procedure binary_search
   A  sorted array
   n  size of array
   x  value ot be searched

   Set lowerBound = 1
   Set upperBound = n 

   while x not found

      if upperBound < lowerBound 
         EXIT: x does not exists.

      set midPoint = lowerBound + ( upperBound - lowerBound ) / 2

      if A[midPoint] < x
         set lowerBound = midPoint + 1

      if A[midPoint] > x
         set upperBound = midPoint - 1 

      if A[midPoint] = x 
         EXIT: x found at location midPoint

   end while

end procedure