Converting hex string to an integer

[Peter Hansen]

Rick Holbert wrote:
> Derek Fountain wrote:
>>Given the character string "0x00A1B2C3" arriving at sys.argv[1] how do I
>>convert that to an integer which I can do some math on?
> 
> i = eval(sys.argv[1])

That's dangerous advice to a newbie if not qualified carefully.

Derek, "eval" could be the source of serious security problems
if you don't understand its power.  Specifically it should
almost never be used for input that comes from a user or
via the command line.  There is pretty much always another
and much better way to do the simple stuff like conversions
than to use eval.

For example, imagine if a malicious could feed your program this:

(on the Linux command line)

   $ myscript "__import_('os').system('rm -rf /')"

or the Windows version:

   C:\> myscript "__import_('os').system('deltree /y c:\*.*')"

Bye-bye filesystem... (don't run these examples!)

-Peter