编写一个日历程序，以2000年为基准，要求输入一个年月，输出对应月份的日历表

执行结果：

代码如下：

#include <stdio.h>
#include <stdlib.h>
#include <assert.h>

int month_day_num[2][13] = {	{0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31},
								{0, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}};//存放每一个月的天数

int IsLeapYear (int year)	//判断是不是闰年
{
	return ((year%4==0&&year%100!=0) || (year%400==0));//是闰年返回1，不是闰年返回零
}
//求一年的第一天是星期几，以2000年为基准(2000年第一天是星期六)
int first_day_of_year(int year)
{
	int i = 0;
	int day_num = 0;
	assert (year > 2000);
	for (i=2000; i<year; i++)
	{
		day_num += (365+IsLeapYear (i));
	}
	return ((day_num+6)%7);
}
//求某一年的某一月第一天是星期几
int first_day_of_month(int year, int month, int first_day)
{
	int i = 0;
	int day_num = 0;
	assert (month>0 && month<13);
	for (i=1; i<month; i++)
	{
		day_num += month_day_num[IsLeapYear (year)][i];
	}
	return (day_num+first_day)%7;
}

void print(int year, int month)
{
	int i = 0;
	int first_day = first_day_of_month(year, month, first_day_of_year(year));
	printf ("%d年%d月：\n", year, month);
	printf ("一\t二\t三\t四\t五\t六\t天\n\n");
	for (i=0; i<first_day-1; i++)
	{
		printf ("\t");
	}
	for (i=0; i<month_day_num[IsLeapYear(year)][month]; i++)
	{
		printf ("%d\t", i+1);
		if ((i+first_day)%7 == 0)
		{
			printf ("\n\n");
		}
	}
	printf ("\n");
}
int main()
{
	int year = 0;
	int month = 0;
	printf ("请按以下格式输入年月：year/month:");
	scanf ("%d/%d", &year, &month);
	printf("\n");
	print(year, month);
	system ("pause");
	return 0;
}