Integers with leading zeroes

Ian Kelly ian.g.kelly at
Sun Jul 19 07:46:08 CEST 2015

On Sat, Jul 18, 2015 at 11:39 PM, Steven D'Aprano <steve at> wrote:
> In Python 2, integer literals with leading zeroes are treated as octal, so
> 09 is a syntax error and 010 is 8.
> This is confusing to those not raised on C-style octal literals, so in
> Python 3 leading zeroes are prohibited in int literals. Octal is instead
> written using the prefix 0o, similar to hex 0x and binary 0b.
> Consequently Python 3 makes both 09 and 010 a syntax error.
> However there is one exception: zero itself is allowed any number of leading
> zeroes, so 00000 is a legal way to write zero as a base-10 int literal.

It's obviously a base-8 literal, not a base-10 literal. :-P

> Does anyone use that (mis)feature?

I don't, but why should it matter?

More information about the Python-list mailing list