IsString

[Steven Bethard]

Steven D'Aprano wrote:
> Judging by the tone of the original poster's question, I'd say for sure he
> is an utter Python newbie, probably a newbie in programming in general,
> so I bet that what (s)he really wants is something like this:
> 
> somefunction("6")
> -> It is a number.
> 
> somefunction("x")
> -> It is a character.
> 
> So, at the risk of completely underestimating Tuvas' level of programming
> sophistication, I'm going to answer the question I think he meant to ask:
> how do I tell the difference between a digit and a non-digit?
> 
> import string
> def isDigit(s):
>     if len(s) != 1:
>         # a digit must be a single character, anything more
>         # or less can't be a digit
>         return False
>     else:
>         return s in string.digits
> 
> 
> If you know that you are only dealing with a single character c, never a
> longer string, you can just use the test:
> 
> c in string.digits

Or better yet, use str.isdigit:

py> '6'.isdigit()
True
py> 'x'.isdigit()
False
py> def is_single_digit(s):
...     return len(s) == 1 and s.isdigit()
...
py> is_single_digit('6')
True
py> is_single_digit('66')
False

STeVe