Pythonic way to determine if a string is a number

[Christian Heimes]

python at bdurham.com schrieb:
> What's the Pythonic way to determine if a string is a number? By
> number I mean a valid integer or float.
> 
> I searched the string and cMath libraries for a similar function
> without success. I can think of at least 3 or 4 ways to build my
> own function.
> 
> Here's what I came up with as a proof-of-concept. Are there
> 'better' ways to perform this type of test?
> 
> Thanks,
> Malcolm
> 
> <code>
> def isnumber( input ):
>     try:
>         if '.' in input:
>             num = float( input )
>         else:
>             num = int( input )
>         return True
> 
>     except ValueError:
>         return False

You code doesn't check for several float representations like "1e10",
"1E10", "inf" and "nan".

Christian