Best way to check if string is an integer?

[John Machin]

On Apr 6, 9:25 am, Mark Dickinson <dicki... at gmail.com> wrote:
> On Apr 5, 6:19 pm, skanem... at yahoo.se wrote:
>
> > which is the best way to check if a string is an number or a char?
> > could the 2nd example be very expensive timewise if i have to check a
> > lot of strings?
>
> You might be interested in str.isdigit:
>
> >>> print str.isdigit.__doc__
>
> S.isdigit() -> bool
>
> Return True if all characters in S are digits
> and there is at least one character in S, False otherwise.
>

This doesn't cater for negative integers.