C語言打印某一年中某月的日歷

#define _CRT_SECURE_NO_WARNINGS 1
#include <stdio.h>
int main()
{
	int arr1[] = { 0,31,28,31,30,31,30,31,31,30,31,30,31 };
	int i = 0;
	int year = 0;
	int month = 0;
	int days = 0;
	int week = 0;//判斷第一天周幾
	scanf("%d%d", &year, &month);
	if((year % 4 == 0 && year % 100 != 0)||(year % 400 == 0))//判斷是否是閏年
	{
	arr1[2] = 29;//閏年2月29天
    }
	for (i = 0; i < month; i++)
	{
		days += arr1[i];//計算該月第一天是該年多少天
	}
	days++;//該月第一天，還要把這一天算上
	//套用計算星期幾的公式
	week = (year - 1 + (year - 1) / 4 - (year - 1) / 100 + (year - 1) / 400 + days) % 7;
	printf(" 日 一 二 三 四 五 六\n");//表頭
	int arr2[50] = {0};
	for (i = 0; i < week; i++)
	{
		printf("   ");//整型數組不能存放空格，因此直接把空格打印出來
	}
	arr2[week] = 1;
	for (i = week + 1; i <= arr1[month]+week-1; i++)//把輸入月份的每一天放到數組中
	{
		arr2[i] = arr2[i-1]+1;
	}
	int count = 0;//記錄已打印幾個數據，打印7個數據就換行
	i = week;
	int flag = 1;//用於記錄是否為第一行，第一行不能用count計數方式換行
	while (i<=arr1[month]+week-1)//把該月所有天數都打印出來
	{
		if (flag <= 7-week)
		{
			printf("%3d", arr2[i]);
			if (flag == 7 - week)//打印夠數據後換行
				printf("\n");
			flag++;
		}
		else
		{
			printf("%3d", arr2[i]);
			count++;
			if (count == 7)
			{
				count = 0;
				printf("\n");
			}
		}
		i++;
	}
	return 0;
}