折半查找

#include
#include
#define  COMPARE(x, y) ((x) < (y) ? -1 : ((x)>(y) ? 1:0))
int compare(int x, int y)
{ 
  if(x   else if(x>y) return 1;
  else  return 0;
}
//---
int binmiddle(int list[], int search, int left, int right)
{
  int mid=0;
  while(left <=  right)
  {
     mid = (left+right)/2;
    switch (COMPARE(list[mid], search)) {
    case -1: left = mid+1; break; 
    case 0:  return mid;  
    case 1:  right = mid-1;
       }
   }
  return -1;
} 
//---递归实现
int binmiddle(int list[], int search, int left, int right)
{
  int mid=0;
  if (left <=  right)
  {
     mid = (left+right)/2;
    switch (COMPARE(list[mid], search)) {
    case -1: return binmiddle(list, search, mid+1, right); 
    case 0:  return mid;  
    case 1:  return binmiddle(list, search, left, mid-1); 
       }
   }
  return -1;
} 

//---
int main(void)
{  
  int r = 0;
  int list[8] = {4,6,7,9,10,12,18,34};
  r = binmiddle(list, 9, 0, 7);
  printf("r is %d \n", r); //r is 5
  return 0;
}
/*--  E  --*/

谢谢欣赏，欢迎指正！