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When I type small integers with a 0 in front into python, they give weird results. Why is this?
>>> 011 9 >>> 0100 64 >>> 027 23 I'm using Python 2.7.3. I have tested this in Python 3.0, and apparently this is now an error. So it is something version-specific.
They are apparently still integers:
>>> type(027) <type 'int'> 
911
Python 3 drops the 0 prefix: integer literals that start with 0 are illegal (except zero itself, and 0x / 0o / 0b prefixes).
Introduction to integersEdit An integer, commonly abbreviated to int, is a whole number (positive, negative, or zero). So 7 , 0 , -11 , 2 , and 5 are integers. 3.14159 , 0.0001 , 11.11111 , and even 2.0 are not integers, they are floats in Python.
Number having 0o or 0O as prefix represents octal number which can have 0 to 7 as one of the digits in it. Example: 0O12: equivalent to 10 (ten) in decimal number system. Number with 0x or 0X as prefix represents hexadecimal number.
In Python, you cannot "set" a value to zero, because zero is the value, and it is immutable. By saying x = 0 you remove the name x from whatever it was before and attach it to the number zero instead. There was a good talk about this topic at this year's PyCon. It is available on Youtube.
These are numbers represented in base 8 (octal numbers). Some examples:
Note: these forms only work on Python 2.x.
011 is equal to 1⋅8¹ + 1⋅8⁰ = 9,
0100 is equal to 1⋅8² + 0⋅8¹ + 0⋅8⁰ = 64,
027 is equal to 2⋅8¹ + 7⋅8⁰ = 16 + 7 = 23.
In Python 3, one must use 0o instead of just 0 to indicate an octal constant, e.g. 0o11 or 0o27, etc. Python 2.x versions >= 2.6 supports both the new and the old format.
0o11 is equal to 1⋅8¹ + 1⋅8⁰ = 9,
0o100 is equal to 1⋅8² + 0⋅8¹ + 0⋅8⁰ = 64,
0o27 is equal to 2⋅8¹ + 7⋅8⁰ = 16 + 7 = 23.
192
In Python 2 (and a few more programming languages), these represent octal numbers.
In Python 3, 011 no longer works and you would use 0o11 instead.
In response to edit: and they are regular integers. They are just specified different way; and they are automatically converted by Python to an internal integer representation (which is base-2 actually, so both 9 and 011 are internally converted to 0b1001).
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