写博客的第一天，学C的第四天

#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
#include<string.h>
#include<windows.h>
#include<stdlib.h>
int main()
{
	/*int a = 0;
	int b = 0;
	int c = 1;
	int d = 1;
	scanf("%d", &b);
	for (a = 1; c < b; ++c)
	{	 
		d = d + 1;
		a = a * d;
		printf("%d ", a);
	}
	return 0;*/

	/*int i = 0;
	int n = 0;
	int ret = 1;
	int sum = 0;
	int a = 0;
	scanf("%d", &a);
	for (n = 1; n <= a; n++)
	{
		ret = 1;
		for (i = 1; i <= n; i++)
		{
			ret = ret * i;
		}
		sum = sum + ret;
	}*/

	/*int i = 0;
	int n = 0;
	int ret = 1;
	int sum = 0;
	int a = 0;
	scanf("%d", &a);
	for (i = 1;i <= a; i++)
	{
		ret = ret * i;
		sum = sum + ret;
		printf("%d ", sum);
	}*/

	//int arr[] = { 1,2,3,4,5,6,7,8,9,10 };
	//int i = 0;
	//int k = 7;
	//int sz = sizeof(arr) / sizeof(arr[0]);//数组元素的个数
	////sizeof表示数据类型或变量所占空间的大小。
	//for (i = 0; i < sz; i++)
	//{
	//	if (k == arr[i])
	//	{
	//		printf("找到了，下标是%d\n",i);
	//		break;
	//	}
	//}
	//if (i == sz)
	//{
	//	printf("找不到");
	//}
	//return 0;

	//折半查找算法、二分查找算法
	/*int k = 0;
	int arr[] = { 1,2,3,4,5,6,7,8,9,10 };
	int sz = sizeof(arr) / sizeof(arr[0]);
	int left = 0;
	int right = sz-1;
	while (left<=right)
	{
		int mid = (left + right) / 2;
		if (arr[mid] > k)
		{
			right = mid - 1;
		}
		else if (arr[mid] < k)
		{
			left = mid + 1;
		}
		else
		{
			printf("找到了，下标是%d", mid);
			break;
		}
	}
	if (left > right)
	{
		printf("找不到\n");
	}
	return 0;*/

	//char arr1[] = "welcome to bit!!!!!!";
	//char arr2[] = "####################";
	//int left = 0;
	//int right = strlen(arr1) - 1;
	//while (left <= right)
	//{
	//	arr2[left] = arr1[left];
	//	arr2[right] = arr1[right];
	//	printf("%s\n", arr2);
	//	Sleep(1000);//休息一秒 1000ms #include<windows.h>
	//	system("cls");//执行系统命令的一个函数-cls-，清空屏幕 #include<stdlib.h>
	//	left++;
	//	right--;
	//}
	//return 0;
	
	int i = 0;
	char password[20] = { 0 };
	for (i = 0; i < 3; i++);
	{
		printf("请输入密码：>");
		scanf("%s", password);
		if (strcmp(password, "123456") == 0)//==不能用来比较两个字符串是否相等，应该使用一个库函数-strcmp
		{
			prinf("登陆成功\n");
			break;
		}
		else
		{
			printf("密码错误\n");
		}
	}
	if (i == 3)
	{
		printf("三次密码均错误，退出程序\n");
	}
	return 0;
}

这是今天学习写的代码