Python datetime formatting without zero-padding

The new string formatting system provides an alternative to strftime. It’s quite readable — indeed, it might be preferable to strftime on that account. Not to mention the fact that it doesn’t zero-pad:

>>> '{d.month}/{d.day}/{d.year}'.format(d=datetime.datetime.now())
'3/1/2012'

Since you probably want zero padding in the minute field, you could do this:

>>> '{d.month}/{d.day}/{d.year} {d.hour}:{d.minute:02}'.format(d=now)
'3/1/2012 20:00'

If you want “regular” time instead of “military” time, you can still use the standard strftime specifiers as well. Conveniently, for our purposes, strftime does provide a code for the 12-hour time padded with a blank instead of a leading zero:

'{d.month}/{d.day}/{d.year} {d:%l}:{d.minute:02}{d:%p}'.format(d=now)
'4/4/2014  6:00PM'

This becomes somewhat less readable, alas. And as @mlissner points out, strftime will fail on some (all?) platforms for dates before 1900.

The other alternate to avoid the "all or none" leading zero aspect above is to place a minus in front of the field type:

mydatetime.strftime('%-m/%d/%Y %-I:%M%p')

Then this: ‘4/10/2015 03:00AM’

Becomes: ‘4/10/2015 3:00AM’

You can optionally place a minus in front of the day if desired.

Edit: The minus feature derives from the GNU C library (“glibc”) as mentioned in the Linux strftime manpage under “Glibc notes”

Good answer from Chris Freeman on Linux.

On windows, it’s:

mydate.strftime('%#m/%#d/%Y')

Thought that might help.

Accepted answer not a proper solution (IMHO) The proper documented methods:

In Linux “#” is replaced by “-“:

%-d, %-H, %-I, %-j, %-m, %-M, %-S, %-U, %-w, %-W, %-y, %-Y

In Windows “-” is replaced by “#”:

%#d, %#H, %#I, %#j, %#m, %#M, %#S, %#U, %#w, %#W, %#y, %#Y

#Linux
mydatetime.strftime('%-m/%d/%Y %-I:%M%p')

# Windows
mydatetime.strftime('%#m/%d/%Y %#I:%M%p')

Source: https://msdn.microsoft.com/en-us/library/fe06s4ak.aspx

As stated by Sagneta: The # hash trick on Windows is only available to native python executable. this will not work for cygwin-based python implementations.

"%l" (that’s a lower-case L) works for the hour (instead of "%I"). I only
know this from another answer here

Python strftime – date without leading 0?

but unfortunately they don’t have the code for the other elements of a date/time.

I use this:

D = str(datetime.now().day)
MM = str(datetime.now().month)
YYYY = str(datetime.now().year)

This, today, will return: 2, 12, 2021

As mentioned by several others, to ignore leading zero on windows, you must use %#d instead of %-d.

For those who like to write clean cross platform python code, without seeing platform switches in business logic, here is a Python3 helper that enables you to have one format string for both Windows, Linux and Others (tested Linux, Windows and FreeBSD):

import os
from datetime import datetime

def dateToStr(d: datetime, fmt: str) -> str:
    return d.strftime(fmt.replace('%-', '%#') if os.name == 'nt' else fmt)

dateToStr(datetime.now(), '%-m/%-d/%-Y')

On a side note, this is another one of those Whaaaaaaaat? features in Python. I don’t understand why they did not create a standard format set for all platforms and add an optional ‘use_native’ flag to use native platform features. Guess it was an early design decision that must be kept for legacy support.

In the official docs formating section:

9. When used with the strptime() method, the leading zero is optional for formats %d, %m, %H, %I, %M, %S, %J, %U, %W, and %V. Format %y does require a leading zero.

So, using %d to parse day in number will automatically parse both 07 & 7 for example.