#include 
  
     
  int bin_search(int key[],int low, int high,int k)  
  {  
     int mid;  
     if(low>high)  
       return -1;  
     else
	 {  
         mid = (low+high) / 2;  
         if(key[mid]==k)  
             return mid;  
         if(k>key[mid])  
             return bin_search(key,mid+1,high,k);        /*在序列的后半部分查找*/  
         else  
             return bin_search(key,low,mid-1,k);            /*在序列的前半部分查找*/  
      }  
 }  
   
 int main()  
 {  
     int n , i , addr;  
     int A[10] = {2,3,5,7,8,10,12,15,19,21};  
      printf("The contents of the Array A[10] are\n");  
      for(i=0;i<10;i++)  
         printf("%d ",A[i]);                                /*显示数组A中的内容*/  
      printf("\nPlease input a interger for search\n");  
      scanf("%d",&n);                                /*输入待查找的元素*/  
      addr = bin_search(A,0,9,n);  
      if(-1 != addr)                                /*查找成功*/  
         printf("%d is at the %dth unit is array A\n ",n,addr);  
      else 
  

	 printf("There is no %d in array A\n",n);            /*查找失败*/  
       getchar();  
       return 0;  
  }