public class HalfSearch {

 public static int halfSearch(int a[], int x) {

  int mid, left, right;

  left = 0;

  right = a.length - 1;

   mid = (left + right) / 2;

  while (a[mid] != x) {

   if (x > a[mid]) {

    left = mid + 1;

   }

   else if (x < a[mid]) {

    right = mid - 1;

   }

            mid=(left+right)/2;

  }

  return mid;

 }

 public static void main(String[] args) {

  int a[] = { 1, 2, 3, 4, 5, 6,7,8,9,10 };

  for (int i = 0; i < a.length; i++) {

   System.out.print(a[i] + "  ");

  }

  System.out.println();

  int s = 10;

  int index = halfSearch(a, s);

  System.out.println(s + "在数组中的下标是  " + index);

 }

}