python value assignment error (whats wrong with 08, 09)

Question

I observed this peculiar behavior while trying to assign a integer value to a variable. What is the possible explanation?

>>> a = 01
>>> a = 02
>>> a = 03
>>> a = 04
>>> a = 05
>>> a = 06
>>> a = 07
>>> a = 08
  File "<stdin>", line 1
    a = 08
         ^
SyntaxError: invalid token
>>> a = 09
  File "<stdin>", line 1
    a = 09
         ^
SyntaxError: invalid token

I'm using python 2.7.6, gcc 4.8.2.

score 4 · Answer 1 · 2016-03-02T12:40:09.750

4

08 octal is 10 decimal. Write 010.

01 == 1
02 == 2
# ...
07 == 7
010 == 8
011 == 9
012 == 10
# ...
017 == 15
020 == 16

edited Mar 02 '16 at 12:40

answered Mar 02 '16 at 12:32

Ohh... old C notations. – vyi Mar 02 '16 at 12:39
Every programming language I know uses this notation for octal numbers. What would you do? – Mar 02 '16 at 12:39
VBA doesn't, out of interest. – Bathsheba Mar 02 '16 at 12:41
I didn't know that. I did use `hex` numbers a lot but **never** had to deal with octal. And now I know. – vyi Mar 02 '16 at 12:42
In Python 3 even `01` is invalid. You'll have to use `0o1`. – Matthias Mar 02 '16 at 12:42
@Matthias Thats a better (more explicit) notation. Do you agree? – vyi Mar 02 '16 at 12:43
1

I like the explicit approach. – Matthias Mar 02 '16 at 12:44

score 2 · Accepted Answer · answered Mar 02 '16 at 12:32

2

A number starting with 0 is an octal literal.

8 is an invalid octal digit, so 08 makes no sense. Ditto 09.

Drop the leading zeros, even if they did make your source code look pretty.

answered Mar 02 '16 at 12:32

Bathsheba

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python value assignment error (whats wrong with 08, 09)

2 Answers2