用C语言判断每年每个月的天数

#include<stdio.h>
int r_year(int y)
{
	if (y % 4 == 0 && y % 100 != 0 || y % 400 == 0)
		return 1;
	else
		return 0;
}
int day(int y, int m)
{
	int days[] = { 0,31,28,31,30,31,30,31,31,30,31,30,31 };
	int d = days[m];
	if (r_year(y) == 1 && m == 2)
		d += 1;
	return d;
}
int main()
{
	int year = 0;
	int month = 0;
	scanf("%d %d", &year, &month);
	int days = day(year,month);
	printf("%d\n", days);
	return 0;
}