例八.txt

这是一本java基础教程 对新手上路有很大帮助

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+"是数组中的第"+middle+"个元素"); 
    }
}