binary search to find an integer on an array - CSharp Data Structure Algorithm

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Description

binary search to find an integer on an array

Demo Code

using System;//from  w  ww.  j  a  v  a2  s .  c  o m
public class MainClass
{
   static void Main()
   {
      var generator = new Random();
      var data = new int[15];
      // fill array with random ints in range 10-99
      for (var i = 0; i < data.Length; ++i)
      {
         data[i] = generator.Next(10, 100);
      }
      Array.Sort(data); // elements must be sorted in ascending order
      DisplayElements(data, 0, data.Length - 1); // display array
      Console.Write("\nPlease enter an integer value (-1 to quit): ");
      int searchInt = int.Parse(Console.ReadLine());
      // repeatedly input an integer; -1 terminates the app
      while (searchInt != -1)
      {
         // perform binary search
         int position = BinarySearch(data, searchInt);
         if (position != -1) // integer was found
         {
            Console.WriteLine($"The integer {searchInt} was found in " + $"position {position}.\n");
         }
         else // integer was not found
         {
            Console.WriteLine($"The integer {searchInt} was not found.\n");
         }
         Console.Write("Please enter an integer value (-1 to quit): ");
         searchInt = int.Parse(Console.ReadLine());
      }
   }
   public static int BinarySearch(int[] values, int searchElement)
   {
      var low = 0; // low end of the search area
      var high = values.Length - 1; // high end of the search area
      var middle = (low + high + 1) / 2; // middle element
      do
      {
         // display remaining elements of array
         DisplayElements(values, low, high);
         // indicate current middle; pad left with spaces for alignment
         Console.WriteLine("-- ".PadLeft((middle + 1) * 3));
         // if the element is found at the middle
         if (searchElement == values[middle])
         {
            return middle; // search key found, so return its index
         }
         // middle element is too high
         else if (searchElement < values[middle])
         {
            high = middle - 1; // eliminate the higher half
         }
         else // middle element is too low
         {
            low = middle + 1; // eliminate the lower half
         }
         middle = (low + high + 1) / 2; // recalculate the middle
      } while (low <= high);
      return -1; // search key was not found
   }
   public static void DisplayElements(int[] values, int low, int high)
   {
      Console.Write(string.Empty.PadLeft(low * 3));
      for (var i = low; i <= high; ++i)
      {
         Console.Write($"{values[i]} ");
      }
   }
}

Result


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