"Fredrik Lundh" <[EMAIL PROTECTED]> wrote in message
news:[EMAIL PROTECTED]
> Terry Reedy wrote:
>> int(somestring) without a radix argument requires that somestring be an
>> decimal integer literal and nothing more and nothing else.
>
> but specifying a radix won't help you, though:
My statement as intended to be read, in its totality, is exactly true.
Remove 'without a radix argument', which is the case under discussion, and
it becomes false unless 'decimal' is also removed. But then one must
specify that the radix match the literal. If somestring is a non-decimal
integer literal (something else), then radix is necessary, and not just
helpful, for correct execution.
>>> int('033')
33
>>> int('033', 8)
27
>>> int('1a3')
Traceback (most recent call last):
File "<stdin>", line 1, in ?
ValueError: invalid literal for int(): 1a3
>>> int('1a3',16)
419
>>> int('4',3)
Traceback (most recent call last):
File "<stdin>", line 1, in ?
ValueError: invalid literal for int(): 4
I presume you know this. I also would have thought that you would know
better than to think that I am so ignorant and foolish as to think that
explicitly giving a default parameter value (which is a no-op of no effect)
would somehow magically fix an invalid input.
The essential point of my post was to clarify for the OP that the reason
int(1.0) does not work is not because 1.0 is a float literal (which is
irrelevant to int) but because it is something more (and not 'nothing
more') than a decimal integer literal. And so I gave the additional
example of int(1x) not working.
Knowing that int stops scanning at the first invalid-for-the-radix 'digit'
explains why it cannot autoconvert a string whose unseen continuation makes
it float literal. If one mistakingly assumes that int uses the same lexer
as Python itself, then one will mistakenly conclude the int will be
informed that the string constitutes a float literal. If this were true,
then expecting the int of the corresponding float value would be
reasonable.
Even when people know that scanning stops, they often are surprised by the
exception being raised. (Indeed, the design could have been otherwise.)
Clp periodically gets posts like "My string s equal to '123abc' starts with
a valid decimal integer literal, so why does int(s) fail?" and "You mean I
really have slice the int away from the rest?" So I thought it worthwhile
to reiterate 'nothing more'.
Terry J.Reedy
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