根据日期算出相隔天数

mdays = [0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]

# 判断是否闰年
def (year):
    return year % 4 == 0 and (year % 100 != 0 or year % 400 == 0)

# 输入日期返回相隔天数
def get_order_days(year, month, day, nyear, nmonth, nday):
    # 分为年月相同的情况，年同月不同，以及年月均不相同三种情况
    year_diff = nyear - year
    month_diff = nmonth - month
    if year_diff == 0:
        if month_diff == 0:
            return nday - day
        else:
            # 计算从起始月一号到最后日期的天数再减去开始的天数
            sum_day = 0
            for m in range(month, nmonth):
                num_day = mdays[m] + (m == 2 and isleap(year))
                sum_day += num_day
            return sum_day + nday - day
    else:
        old_days = 0
        new_days = 0
        year_days = 0
        for m in range(month, 13):
            num_day = mdays[m] + (m == 2 and isleap(year))
            old_days += num_day
        old_days -= day
        for m in range(1, nmonth):
            num_day = mdays[m] + (m == 2 and isleap(year))
            new_days += num_day
        new_days += nday
        for y in range(year+1, nyear):
            if isleap(y):
                year_days += 366
            else:
                year_days += 365
    sumdays = old_days + new_days + year_days
    print(sumdays)
    return old_days + new_days + year_days


get_order_days(2011,6,30 ,2017,6,30)