C语言编程之初识数组线性查找和二分查找

#include <stdio.h>
int main(void)
{
	int arr[] = { 5,4,6,8,7,9,10,2,3,1 };
	int len = sizeof(arr) / sizeof(arr[0]);//计算数组的元素个数
	int i;
	int n;
	scanf("%d", &n);//输入要查找的元素
	for (i = 0; i < len; i++)
	{
		if (arr[i] == n)
		{
			printf("%d的下标是%d\n", n, i);
			break;//找到后就直接跳出循环
		}
	}
	if (i == len)//因为如果数组元素全部遍历一遍后，都没有i++等于len后，便跳出循环再判断说不存在。
		printf("Don't have number %d\n", n);	
	return 0;
}

#include <stdio.h>
int main(void)
{
	int n;
	scanf("%d", &n);
	int arr[] = { 1,2,3,4,5,6,7,8,9,10};
	int len = sizeof(arr) / sizeof(arr[0]);
	int left = 0;
	int right = len - 1;
	int mid;
	while (left <= right)
	{
		mid = (left + right) / 2;
		if (arr[mid] > n)
		{
			right = mid-1;
		}
		else if (arr[mid] < n)
		{
			left = mid+1;
		}
		else 
		{
			break;
		}
	}
	if (left <= right)
		printf("%d的下标是%d\n", n, mid);
	else 
		printf("DON't have number %d\n", n);
	return 0;
}
	/*int i = 1;

left = mid+1;
right = mid-1;

right = mid;
left = mid;