用二分查詢法在一維有序陣列中查詢某個值並輸出其下標值
阿新 • • 發佈:2019-02-14
關鍵字與左右標的大小比較
#include<stdio.h>
int main()
{
int arr[] = { 0, 1, 2, 3, 4, 6, 7, 9 };
int left = 0;
int right = sizeof(arr) / sizeof(arr[0])-1;
int mid = 0;
int key = 4;
while (left <= right)
{
mid=(left + right) / 2;
if (arr[mid]>key)
{
right = mid - 1;
}
else if (arr[mid] < key)
{
left = mid + 1;
}
else
break;
}
if (left <= right)
{
printf("找到了下標是%d\n", arr[mid]);
}
else
{
printf("找不到");
}
return 0;
}