how to get the same day of next month of a given day in python using datetime

Question

i know using datetime.timedelta i can get the date of some days away form given date

daysafter = datetime.date.today() + datetime.timedelta(days=5)


        

Answer 1

Of course there isn't -- if today's January 31, what would be "the same day of the next month"?! Obviously there is no right solution, since February 31 does not exist, and the datetime module does not play at "guess what the user posing this impossible problem without a right solution thinks (wrongly) is the obvious solution";-).

I suggest:

try:
  nextmonthdate = x.replace(month=x.month+1)
except ValueError:
  if x.month == 12:
    nextmonthdate = x.replace(year=x.year+1, month=1)
  else:
    # next month is too short to have "same date"
    # pick your own heuristic, or re-raise the exception:
    raise

Answer 2

This work for me

import datetime
import calendar


def next_month_date(d):
    _year = d.year+(d.month//12)
    _month =  1 if (d.month//12) else d.month + 1
    next_month_len = calendar.monthrange(_year,_month)[1]
    next_month = d
    if d.day > next_month_len:
        next_month = next_month.replace(day=next_month_len)
    next_month = next_month.replace(year=_year, month=_month)
    return next_month

usage:

d = datetime.datetime.today()
print next_month_date(d)

Answer 3

I often need to need to keep the date as last in month when adding months. I try to add the amount of months to the day after and then remove one day again. If that fails I add one more day until success.

from datetime import timedelta

DAY = timedelta(1)

def add_months(d, months):
    "Add months to date and retain last day in month."
    d += DAY
    # calculate year diff and zero based month
    y, m = divmod(d.month + months - 1, 12)
    try:
        return d.replace(d.year + y, m + 1) - DAY
    except ValueError:
        # on fail return last day in month
        # can't fail on december so just adding one more month
        return d.replace(d.year + y, m + 2, 1) - DAY

Answer 4

from datetime import timedelta
try:
    next_month = (x.replace(day=28) + timedelta(days=7)).replace(day=x.day)
except ValueError:  # assuming January 31 should return last day of February.
    next_month = (x + timedelta(days=31)).replace(day=1) - timedelta(days=1)

Answer 5

This is how I solved it.

from datetime import date
try:
    (year, month) = divmod(date.today().month, 12)
    next_month = date.today().replace(year=date.today().year+year, month=month+1)
except ValueError:
    # This day does not exist in next month

You can skip the try/catch if you only want the first day in next month by setting replace(year=date.today().year+year, month=month, day=1). This will always be a valid date since we have caught the month overflow using divmod.

Answer 6

You can use calendar.nextmonth (from Python 3.7).

>>> import calendar
>>> calendar.nextmonth(year=2019, month=6)
(2019, 7)
>>> calendar.nextmonth(year=2019, month=12)
(2020, 1)

But be aware that this function isn't meant to be public API, it's used internally in calendar.Calendar.itermonthdays3() method. That's why it doesn't check the given month value:

>>> calendar.nextmonth(year=2019, month=60)
(2019, 61)

In Python 3.8 is already implemented as internal function.