求某一年的某一月有多少天

#include <stdio.h>
#include <windows.h>
#include <conio.h>

int GetYearMonth(int year, int month);
int CalCommonLeapYear(int year);

int main() {
	//求某一年的某一月有多少天
	int year = 0, month = 0, rdays = 0;
	scanf_s("%d",&year);
	scanf_s("%*[^\n]"); scanf_s("%*c");
	scanf_s("%d", &month);
	
	rdays = GetYearMonth(year, month);

	printf("year=%d,month=%d is days =%d\n", year, month,rdays);

	return 0;
}


int GetYearMonth(int year, int month) {
	int isLeap = 0;
	switch (month)
	{
	case 1:
	case 3:
	case 5:
	case 7:
	case 8:
	case 10:
	case 12:
		return 31;
	case 4:
	case 6:
	case 9:
	case 11:
		return 30;
	default:
		//計算平年還是閏年
		isLeap = CalCommonLeapYear(year);
		if (isLeap == 1) {
			return 28;
		}
		else {
			return 29;
		}
		break;
	}
}

//如果返回是1，說明平年，2說明閏年
int CalCommonLeapYear(int year) {
	int i = 0;

	if ((year % 4 == 0 && year % 100 != 0) || (year % 100 == 0) || (year % 400 == 0)) {
		i= 2;
	}
	else {
		i = 1;
	}

	return i;
}