srtring to int question

[Bernhard Herzog]

"Darrell Gallion" <darrell at dorb.com> writes:

> Dooo@!
> Those examples make more sense like this.
> The re prevents bad things from being input into eval.
> 
> def convert(s):
>     try:
>         x = int(s)
>     except:
>         print "Not a number"
>         return None
>     return x
> 
> def convert(s):
>     try:
>         assert(re.match("\s*\d+",s))

Using assert for this is a bad idea. Assert statements will be omitted
if the code is optimized (Python's -O option). They're meant to check
internal program state and invariants, not to validate user input.

The regex used has a bug, btw. It doesn't allow signs, e.g. "-1" will
not be matched.

>         x=eval(s,{},{})
>     except:
>         print "Not a number"
>         return None
>     return x

-- 
Bernhard Herzog   | Sketch, a drawing program for Unix
herzog at online.de  | http://sketch.sourceforge.net/