Optimizing a binary search algorithm

Question

I have implemented a binary search algorithm in C#. Can anyone give me suggestions on improving its effectiveness?

using System;

namespace bs2
{
    class Program
    {
        static void Main(string[] args)
        {
            int n = int.Parse(Console.ReadLine());
            int[] arr = new int[n];

            for(int i=0;i<n;i++)
            {
                arr[i] = i*14; //14 is a random number, I multiply by a number so that arr[i] would not be equal to i.
            }

            int searchingfor = int.Parse(Console.ReadLine());
            int min = 0;int max = n-1;int mid = (n-1)/2;
            while (true)
            {
                if (arr[mid] == searchingfor)
                {
                    Console.WriteLine("Element is on position {0}", mid);
                    break;
                }else if (arr[mid] < searchingfor)
                {
                    min = mid;
                    mid = (min + max) / 2;
                }else if (arr[mid] > searchingfor)
                {
                    max = mid;
                    mid = (min + max) / 2;
                }
            }

        }
    }
}

Answer 1

The core of your search algorithm is OK except for one thing:

The while(true) loop will run forever, if the searchingFor is not in the array.

In addition you should organize your code properly by separating functionality: test input/output in one function and the algorithm in another:

void TestBinarySearch()
{
  Console.Write("Enter Array Length: ");
  int length = int.Parse(Console.ReadLine());
  Console.Write("Enter Search Target: ");
  int target = int.Parse(Console.ReadLine());

  Random rand = new Random(5);
  int[] data = Enumerable.Range(0, length).Select(n => rand.Next(length)).OrderBy(d => d).ToArray();
  int foundIndex = BinarySearch(data, target);
  if (foundIndex >= 0)
    Console.WriteLine($"Target found at: {foundIndex}");
  else
    Console.WriteLine("Target not found");
}

int BinarySearch(int[] data, int target)
{
  int min = 0;
  int max = data.Length - 1;
  int mid = (data.Length - 1) / 2;

  while (min != mid && max != mid)
  {
    if (data[mid] == target)
    {
      return mid;
    }

    if (data[mid] < target)
    {
      min = mid;
      mid = (min + max) / 2;
    }
    else if (data[mid] > target)
    {
      max = mid;
      mid = (min + max) / 2;
    }
  }

  return -1;
}

Answer 2

It fails (loops infinitely) if the number is not in the array

You fail to test on possible duplicate values

You don't need mid = (min + max) / 2; in two spots and it can overflow

You can add or subtract 1 as you know the current mid is not good

The wiki implementation is simpler and faster
I know missing if else { }

int left = 0;
int right = array.Length - 1;
while (left <= right)
{
    int middle = left + (right - left) / 2;
    if (array[middle] > target)
        right = middle - 1;
    else if (array[middle] < target)
        left = middle + 1;
    else
        return middle;
}
return null;