Python f-string formatting not working with strftime inline

Question

I'm hitting an odd error that I'm trying to understand. Doing some general code cleanup and converting all string formatting to f-strings. This is on Python 3.6.6

This code does not work:

from datetime import date
print(f'Updated {date.today().strftime('%m/%d/%Y')}')

  File "<stdin>", line 1
    print(f'Updated {date.today().strftime('%m/%d/%Y')}')
                                               ^
SyntaxError: invalid syntax

However, this (functionally the same) does work:

from datetime import date
d = date.today().strftime('%m/%d/%Y')
print(f'Updated {d}')

Updated 11/12/2018

I feel like I'm probably missing something obvious, and am fine with the second iteration, but I want to understand what's happening here.

note the colors in your question: you have to use a different set of quotes. Do `print(f'Updated {date.today().strftime("%m/%d/%Y")}')` — Jean-François Fabre, Nov 12 '18 at 20:33

score 65 · Accepted Answer · answered Dec 04 '20 at 14:36

65

There's a native way:

print(f'Updated {date.today():%m/%d/%Y}')

More on that:

answered Dec 04 '20 at 14:36

George Sovetov

4,942
5
36
57

score 12 · Answer 2 · answered Nov 12 '18 at 20:45

12

print(f'Updated {date.today().strftime("%m/%d/%Y")}')

Your code was prematurely ending the string definition.

answered Nov 12 '18 at 20:45

Rich Tier

9,021
10
48
71

Wow, yep, super obvious. Thanks for pointing out the stupid mistake! – Sam Morgan Nov 12 '18 at 21:08
14

`print(f'Updated {date.today():"%m/%d/%Y"}')` – Kubas Dec 06 '19 at 14:46

score 3 · Answer 3 · answered Nov 12 '18 at 20:59

3

if string is part of another string you need to use double quote in one of them

(f"updated {date.today().strftime('%D')}") # %m/%d/%y can also be written %D

answered Nov 12 '18 at 20:59

ratan kamath

41
6

escaping the (inner) single quotes would also work, though there's no reason to prefer that here. `f'updated {date.today().strftime(\'%D\')}'` – Adam Smith Nov 12 '18 at 21:05
Ah, nice tip on %D. Where did you find this? I can't find that reference anywhere in documentation. – Sam Morgan Nov 14 '18 at 18:54
3

i found it here ' https://www.tutorialspoint.com/python/time_strftime.htm ' some of which are not in documentation i guess – ratan kamath Nov 15 '18 at 06:06

score 2 · Answer 4 · answered Mar 16 '22 at 07:42

2

Strangely this has not been proposed:

print(date.today().strftime("Updated: %m/%d/%Y"))

answered Mar 16 '22 at 07:42

Paal Pedersen

1,070
1
10
13

1

a funnier way to use f strings with strftime: var = 'Updated' print(date.today().strftime(f'{var}: %m/%d/%Y')) – Paal Pedersen Mar 16 '22 at 10:00

Python f-string formatting not working with strftime inline

4 Answers4

Linked