Why does Python change the value of an integer when there is a 0 in front of it?

Question

I implemented a function converting an integer number to its representation as a string intToStr() (code below).

For testing I\'ve passed in some values

Answer 1

An integer literal starting with a 0 is interpreted as an octal number, base 8:

>>> 01223
659

This has been changed in Python 3, where integers with a leading 0 are considered errors:

>>> 01223
  File "", line 1
    01223
        ^
SyntaxError: invalid token
>>> 0o1223
659

You should never specify an integer literal with leading zeros; if you meant to specify an octal number, use 0o to start it, otherwise strip those zeros.