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I am new to Python, in a way new to programming.

Was trying to teach myself python from the basics... and came across this weird thing...

Please find below the printing results...

>>> print 1,000,000
1 0 0
>>> print 1,112,231
1 112 231
>>> print 000
0
>>> print 1,001,002
1 1 2
>>> print 1,100,001,0010
1 100 1 8

While I do understand that 0010 is the binary equivalent of 8 (in the last one), I do not understand why does Python do so? Is it some embedded logic of the language or something else?

The remaining, I was able to figure out; however if anyone can give a brief explanation it would be great!

Oleh Prypin
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user3503790
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  • Can you post the code that does that? What are you trying to do? print a binary representation of 8? Do you want to see `1000` instead of 8? (btw, `0010` is 2, in binary, 8 in octal. You're probably seeing octal, not binary) – Savir Apr 06 '14 at 17:42

2 Answers2

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As said in the comment:

When you start a number by 0 in Python, it assumes it's an Octal number. See this question: What do numbers starting with 0 mean in python?

So what you're seeing in the last case is the decimal representation of the octal 10, which is 8 in decimal:

0010 --> 0*8^2 + 1*8^1 + 0*8^0

If you do print 0111 you'll see 73, because it's 1*8^2 + 1*8^1 + 1*8^0 (64 + 8 + 1)

The print 000 is still printing the decimal representation of the octal 000, but zero in base 8 is the same as 0 in base 10.

EDIT: Thanks to @AdamSmith for pointing the new behavior in Python 3.

Community
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Savir
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    Note that this isn't true anymore in Python3. Now you must explicitly use `0o111` (to match the format of `0x` and `0b`) – Adam Smith Apr 06 '14 at 18:06
  • @AdamSmith, Interesting... (and useful addition). I'm still stuck with Python 2.7 **:-D** – Savir Apr 06 '14 at 18:07
  • @AdamSmith I tested this on my home Python 2.7.6 and it works the same way. Apparently 0111 and 0o111 give the same result. – sabbahillel Apr 06 '14 at 18:51
  • @sabbahillel yes but in Python3 `0111` will be `111` not `73` – Adam Smith Apr 06 '14 at 21:36
  • @AdamSmith THanks, I will have to remember this and be careful to get in the habit of '0o' no matter which version I run. That way, I will avoid making the misteak [sic] – sabbahillel Apr 07 '14 at 00:02
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    @BorrajaX I apologize for putting the edit in your answer. I hit the wrong answer edit. Please reject it as I do not know how to cancel it. – sabbahillel Apr 07 '14 at 00:14
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Python literals preceded by '0' tells it to express in in octal. literals preceded by '0x' are hexadecimal. literals preceded by '0b' are binary.

print 0010
8

print 0b110011
51

print 0x100
256

I have also tested the '0o' on my python 2.7.6 and gotten

print 0o111 # number 0 letter o followed by digits
73

Note that Python 3 will print 0111 as 111 as it is supposed to treat a leading 0 as part of the decimal number unless it is followed by 'x', 'o', or 'b' I do not have Python 3 so I cannot test this myself.

Thanks to @AdamSmith for pointing this out in his comment.

sabbahillel
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