Python add leading zeroes using str.format

Question

Can you display an integer value with leading zeroes using the str.format function?

Example input:

"{0:some_format_specifying_width_3}".format(1)
"{0:some_format_specifying_width_3}".format(10)
"{0:some_format_specifying_width_3}".format(100)

Desired output:

"001"
"010"
"100"

I know that both zfill and %-based formatting (e.g. '%03d' % 5) can accomplish this. However, I would like a solution that uses str.format in order to keep my code clean and consistent (I’m also formatting the string with datetime attributes) and also to expand my knowledge of the Format Specification Mini-Language.

Asked By: butch

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Source

Answer 1

>>> "{0:0>3}".format(1)
'001'
>>> "{0:0>3}".format(10)
'010'
>>> "{0:0>3}".format(100)
'100'

Explanation:

{0 : 0 > 3}
 │   │ │ │
 │   │ │ └─ Width of 3
 │   │ └─ Align Right
 │   └─ Fill with '0'
 └─ Element index

Answered By: Andrew Clark

Answer 2

Derived from Format examples, Nesting examples in the Python docs:

>>> '{0:0{width}}'.format(5, width=3)
'005'

Answered By: msw

Python add leading zeroes using str.format

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