Example3_8

import java.util.Scanner;
public class Example3_8{
 public static void main(String args[]){
  int n,start,end,middle;
  int a[]={-2,1,4,5,8,12,17,23,45,56,90,100};
  start=0;
  end=a.length;
  middle=(start+end)/2;
  int count=0;
  Scanner reader=new Scanner(System.in);
  System.out.print("请输入一个整数:");
  n=reader.nextInt();
  while(n!=a[middle]){
   if(n>a[middle]){
    start=middle;
  }
  else if(n<a[middle]){
   end=middle;
  }
  middle=(start+end)/2;
  count++;
  if(count>a.length/2)
  break;
 }
 if(count>a.length/2)
  System.out.println(n+"不在数组中");
 else
  System.out.println(n+"是数组中"+middle+"个元素");
 }
}