2020-05-20

用递归方法实现二分查找，为了避免异常情况，首先判断上下限范围

int binarysearch(int source[],int low,int,high,int targetvalue)
{
   if (low>high) return;
   int temp= (high-low)/2+low;
   if(source[temp]>targetvalue)
       binarysearch(source,low,temp-1,targetvalue);
  else if(source[temp]<targetvalue)
    binarysearch(source,temp+1,high,targetvalue);
   else
       return temp;
}