练习四：日期计算（输入某年某月某日计算出这一天是该年第几天的方法）

实现输入某年某月某日计算出这一天是该年第几天的方法
方法一：笨办法

list_day = [0,31,28,31,30,31,30,31,31,30,31,30,31]
year = int(input('请输入年'))
month = int(input('请输入月'))
day = int(input('请输入日'))
month_day = 0
if 0<month<=12:
    if year % 400 == 0 or ((year % 4 ==0) and (year % 100 != 0)):
        print('{}是闰年'.format(year))
        list_day[1] = 29
        for i in range(month-1):
            month_day += list_day[i]
        if day <= list_day[month]:
            count_day = month_day + day
            print(count_day)
        else:
            print('day error')

    else:
        for i in range(month):
            month_day += list_day[i]
        if day <= list_day[month]:
            count_day = month_day + day
            print(count_day)
        else:
            print('day error')
else:
    print('month error')

方法二：简化方法一

list_day = [0,31,28,31,30,31,30,31,31,30,31,30,31]
year = int(input('请输入年'))
month = int(input('请输入月'))
day = int(input('请输入日'))
if 0< month <=12:
    sum = list_day[month-1]
else:
    print('data error')
sum += day

leap = 0 #
if year % 400 == 0 or ((year % 4 ==0) and (year % 100 != 0)):
    leap = 1
if leap == 1 and month > 2:
    sum += 1
print(sum)

方法三：使用模块time和datetime

import datetime
import time
def function2(year, month, day): # 直接使用Python内置模块datetime的格式转换功能得到结果
    date = datetime.date(year, month, day)
    return date.strftime('%j')
print(function2(2018,12,3))