Danny Yoo wrote:
>
> ---------- Forwarded message ----------
> Date: Sun, 29 Oct 2006 12:33:58 -0500
> From: Kristinn Didriksson <[EMAIL PROTECTED]>
> To: Danny Yoo <[EMAIL PROTECTED]>
> Subject: Re: [Tutor] name is not defined error
>
> Hi Danny,
> Thanks :)
> The program works now. I'll take a look at those threads.
> Here is what the book says " This function (eval) takes any string and
> evaluates it as if it were a Python expression." I took that to mean that it
> would turn a sting into an integer. Oops.
eval() evaluates a Python expression and returns a value. This is
similar to what happens when you enter text on the command line. eval()
will take a string like '123' and turn it into the integer 123. eval()
will also take the string 'import shutil;shutil.rmtree("/")' and turn it
into a really bad day. A better way to convert a string that represents
an integer into an integer is to use the int() function.
Danny's warnings apply, I just wanted to clarify eval() a bit.
Kent
> it is a little confusing to get started, but lots of practice will change
> that.
> Thanks for your help.
> Regards,
> Kristinn
>
> On Oct 29, 2006, at 12:15 PM, Danny Yoo wrote:
>
>>
>>> It is my understanding that eval turns a string into a number and then I
>>> can
>>> do math operations on it.
>> Hi Kristinn,
>>
>> No, no, that's not what it does. *grin*
>>
>> Where did you read about eval() from? If you saw it in a beginner's
>> tutorial, tell us who the guilty party is so we can knock some sense into
>> that tutorial.
>>
>> Don't use eval(): it's "unsafe" in the sense that it does something much
>> more
>> than what one might expect. I won't say too much more about it at the
>> moment,
>> but if you're interested, see the threads:
>>
>> http://mail.python.org/pipermail/tutor/2001-September/008967.html
>> http://mail.python.org/pipermail/tutor/2004-December/033828.html
>>
>> for examples. Again, I have to say this again: don't use eval() unless you
>> really know what you're doing.
>>
>>
>> Anyway, I think you're looking for the ord() function:
>>
>> http://docs.python.org/lib/built-in-funcs.html#l2h-55
>>
>> Its inverse is the chr() function:
>>
>> http://docs.python.org/lib/built-in-funcs.html#l2h-15
>>
>> Good luck!
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