20. 折半查找有序数组

 1 //折半查找  前提有序数组
 2 #include <stdio.h>
 3 #define N 10
 4 int main(void)
 5 {
 6     int arr[N] = {1,2,3,4,5,6,7,8,9,10};//升序
 7     int findDate = 10;
 8     int idx = -1;
 9     int left = 0,right=N-1;
10     int mid;
11 
12     while(left<=right)
13     {
14         mid = (left+right)/2;
15         if(findDate == arr[mid])
16         {
17             idx = mid;
18             break;
19         }
20         else if(findDate > arr[mid])
21         {
22             left = mid+1;
23         }
24         else
25             right = mid-1;
26     }
27     if(idx == -1)
28         printf("find none
");
29     else
30         printf("findDate's idx == %d
",idx);
31 
32 
33     return 0;
34 }