Fixed width number formatting python 3

Question

How do I get an integer to fill 0's to a fixed width in python 3.2 using the format attribute? Example:

a = 1
print('{0:3}'.format(a)} 

gives ' 1' instead of '001' I want. In python 2.x, I know that this can be done using

print "%03d" % number. 

I checked the python 3 string documentation but wasn't able to get this.

http://docs.python.org/release/3.2/library/string.html#format-specification-mini-language

Thanks.

Answer 1

Prefix the width with a 0:

>>> '{0:03}'.format(1)
'001'

Also, you don't need the place-marker in recent versions of Python (not sure which, but at least 2.7 and 3.1):

>>> '{:03}'.format(1)
'001'

Answer 2

There is built-in string method .zfill for filling 0-s:

>>> str(42).zfill(5)
'00042'
>>> str(42).zfill(2)
'42'