This seems to add the appropriate suffix, and remove the ugly leading zeroes in the day number:

#!/usr/bin/python

import time

day_endings = {
    1: 'st',
    2: 'nd',
    3: 'rd',
    21: 'st',
    22: 'nd',
    23: 'rd',
    31: 'st'
}

def custom_strftime(format, t):
    return time.strftime(format, t).replace('{TH}', str(t[2]) + day_endings.get(t[2], 'th'))

print(custom_strftime('%B {TH}, %Y', time.localtime()))

date and datetime objects (and time as well) support a mini-language to specify output, and there are two ways to access it:

• direct method call: dt.strftime('format here')
• format method (python 2.6+): '{:format here}'.format(dt)
• f-strings (python 3.6+): f'{dt:format here}'

So your example could look like:

• dt.strftime('The date is %b %d, %Y')
• 'The date is {:%b %d, %Y}'.format(dt)
• f'The date is {dt:%b %d, %Y}'

In all three cases the output is:

The date is Feb 23, 2012

For completeness' sake: you can also directly access the attributes of the object, but then you only get the numbers:

'The date is %s/%s/%s' % (dt.month, dt.day, dt.year)
# The date is 02/23/2012

The time taken to learn the mini-language is worth it.

For reference, here are the codes used in the mini-language:

• %a Weekday as locale’s abbreviated name.
• %A Weekday as locale’s full name.
• %w Weekday as a decimal number, where 0 is Sunday and 6 is Saturday.
• %d Day of the month as a zero-padded decimal number.
• %b Month as locale’s abbreviated name.
• %B Month as locale’s full name.
• %m Month as a zero-padded decimal number. 01, ..., 12
• %y Year without century as a zero-padded decimal number. 00, ..., 99
• %Y Year with century as a decimal number. 1970, 1988, 2001, 2013
• %H Hour (24-hour clock) as a zero-padded decimal number. 00, ..., 23
• %I Hour (12-hour clock) as a zero-padded decimal number. 01, ..., 12
• %p Locale’s equivalent of either AM or PM.
• %M Minute as a zero-padded decimal number. 00, ..., 59
• %S Second as a zero-padded decimal number. 00, ..., 59
• %f Microsecond as a decimal number, zero-padded on the left. 000000, ..., 999999
• %z UTC offset in the form +HHMM or -HHMM (empty if naive), +0000, -0400, +1030
• %Z Time zone name (empty if naive), UTC, EST, CST
• %j Day of the year as a zero-padded decimal number. 001, ..., 366
• %U Week number of the year (Sunday is the first) as a zero padded decimal number.
• %W Week number of the year (Monday is first) as a decimal number.
• %c Locale’s appropriate date and time representation.
• %x Locale’s appropriate date representation.
• %X Locale’s appropriate time representation.
• %% A literal '%' character.