The binary search algorithm quickly searches a large array of numbers, itâ€™s often referred to as divide and conquer.

public class BinarySearch { public int BinarySearch(int[] items, int searchValue) { int left = 0; int right = items.Length - 1; while (left <= right) { var middle = (left + right) / 2; //If the searchValue is in the center, we found it! if(items[middle] == searchValue) { return middle; } //If the searchValue is less than the current middle, we set the right to (middle - 1) //Because the searchValue is in the lower half of the items. if(searchValue < items[middle]) { right = middle - 1; } //If the searchValue is greater than the current middle, we set the right to (middle + 1) //Because the searchValue is in the higher half of the items. else { left = middle + 1; } } // now that we've either found the item and returned it or we've reset our search boundaries // we'll search it again. // Not found. return -1; } }