package main

import "fmt"

func main() {
	days := CalcDaysFromYearMonth(2021, 9)
	fmt.Println(days)
}

func CalcDaysFromYearMonth(year, month int) int8{
	/* 根据年月计算天数 */
	var days int8
	switch month {
	case 1, 3, 5, 7, 8, 10, 12:
		days = 31
	case 4, 6, 9, 11:
		days = 30
	case 2:
		if year%4 == 0 {
			days = 29  // 闰年
		} else {
			days = 28  // 平年
		}
	default:
		days = -1
	}
	return days
}