python 3.4 string manipulation - truncating leading zeros

Question

There are a number of existing posts on this topic, but I cannot get this simple piece of code to work correctly. I have tried many many times with no success...

per = 5


if per < 10 == True:
    ms = 'fwd_%sd' % str(per).zfill(2)
else:
    ms = 'fwd_%sd' % per

and

if per < 10 == True:
    a = format(per, 'fwd_02d')
else:
    a = 'fwd_%sd' % per

The result should be 'fwd_05d' but I can only get 'fwd_5d'.

Among others, I have seen:

Display number with leading zeros

Add leading zero python

Please help!

Padraic Cunningham · Accepted Answer · 2015-06-09T18:16:14.543

2

You can use str.format, if you are actually doing nothing else but padding just use ms = 'fwd_{:02}d'.format(per) and forget the if/else, only numbers less than 10 will be padded with a 0. The 0 in {:02} is what to pad with and the 2 is the size to pad to.

ms = 'fwd_{:02}d'.format(per)

On another note if per < 10 == True: is the same as if per < 10:

edited Jun 09 '15 at 18:16

answered Jun 09 '15 at 18:07

Padraic Cunningham

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Why do we even need `if` here? – Tuan Anh Hoang-Vu Jun 09 '15 at 18:07
@tuananh, why would we not? Maybe there is more logic in the OP's code – Padraic Cunningham Jun 09 '15 at 18:08
Because `'fwd_{:02}d'.format(50) = 50, 'fwd_{:02}d'.format(500) = 500` – Tuan Anh Hoang-Vu Jun 09 '15 at 18:09
@tuananh, the question about leading zeros, I have no idea what the OP is actually doing so I used the code provided – Padraic Cunningham Jun 09 '15 at 18:10
thanks very much Padraic and Martijn, much appreciated. Not sure where my older comments went. – MJS Jun 09 '15 at 21:12

jdf · Answer 2 · 2015-06-09T18:15:03.677

0

You can just create a temp str variable, check if less than 10, and add a zero to the front if needed. Also, you shouldn't have an if statement and then check if it equals true. It is redundant and makes your code less readable.

per = 5

if per < 10:
    perStr = '0' + str(per)

print('fwd_' + perStr + 'd')

edited Jun 09 '15 at 18:15

answered Jun 09 '15 at 18:09

jdf

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python 3.4 string manipulation - truncating leading zeros

2 Answers2