二分法查找一组有序数



#include<stdio.h>
#include<stdlib.h>
int main()
{
 int arr[] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
 int key = 7;
 int left = 0;
 int right = sizeof(arr) / sizeof(arr[0]) - 1;
 while (left <= right)
 {
  int mid = left + (right - left) / 2;//求平均值不会溢出
  if (arr[mid] == key)
  {
   printf("找到了：%d\n", mid);
   break;
  }
  else if (arr[mid] > key)
  {
   right = mid - 1;
  }
  else
  {
   left = mid + 1;
  }
 }
 if (left > right)
 {
  printf("找不到");
 }
 system("pause");
 return 0;
}