折半查找递归与非递归实现

#include<stdio.h>
#define COMPARE(x,y) ( (x<y) ? -1 :( (x==y ) ? 0: 1 ) )

int BinarySearch(int list[],int x,int left ,int right)
{
       int middle;
       while( left<=right )
       {
           middle=(left+right)/2;
           switch( COMPARE( list[middle],x ) )
           {
              case -1: left=middle+1;
                        break;
              case  0 : return middle;
              case  1 : right=middle-1;
           }
       }
       return -1;
}

int BinarySearchRecursive(int list[],int x,int left ,int right)
{
   int middle;
   if( left<=right )
   {
       middle=( left+right )/2;
       switch( COMPARE(list[middle],x) )
       {
          case -1: return BinarySearchRecursive(list,x,left+1,right);
                   
          case 0:  return middle;
          case 1:  return BinarySearchRecursive(list,x,left,middle-1);
       }
   }
   return -1;
}

int main()
{
  int a[10];
  int i;
  for( i=0 ;i<10;i++ )
      a[i]=i;
   
  int result=BinarySearchRecursive(a,3,0,9);
  if(result==-1)
     printf("search fail\n");
  else 
    printf("%d %dth location  in the array  \n",a[result],result+1);
  return -1;
}