A way of checking if a string contains a number

[jason.s.trowbridge at gmail.com]

On Dec 12, 3:10 pm, Hamish <hamishm... at gmail.com> wrote:
> Hey
>
> I'm new to python, but I have used a fair bit of C and Perl
>
> I found Perls regex's to be very easy to use however I don't find
> Pythons regexes as good.
>
> All I am trying to do is detect if there is a number in a string.
>
> I am reading the string from an excel spread sheet using the xlrd
> module
>
> then I would like to test if this string has a number in it
>
> ie.
> import xlrd
> import re
>
> doesHaveNumber = re.compile('[0-9]')
> string1 = ABC 11
>
> regularExpressionCheck = doesHaveNumber.search(string1)
>
> This will get the right result but then I would like to use the result
> in an IF statement and have not had much luck with it.
>
> if regularExpressionCheck != "None"
>       print "Something"
>
> the result is that it prints every line from the spreadsheet to output
> but I only want the lines from the spreadsheet to output.
>
> Is there a way I can drop the regular expression module and just use
> built in string processing?
>
> Why si the output from checks in teh re module either "None" or some
> crazy memory address? Couldn't it be just true or false?

None isn't a string, None is a special object under Python.  Functions
that don't return anything actually return the None value.  In a
boolean context, None is false.

Python objects can be used in a boolean context, such as an if-
statement.  Empty sequences (such as tuples, strings, and lists),
None, 0, and 0.0 are treated as False.  Everything else is usually
treated as "True".  If a class defines a __len__ or __nonzero__
method, those methods are called to determine if an instance is True
or False.  Otherwise, all objects are True.

There's also only one None object, so identity testing is the pythonic
idiom for testing against None.

So, your check needs to be:
if regularExpressionCheck is not None:
  print "Something"

or, even more simply:
if regularExpressionCheck:
  print "Something"

I recommend that you peruse a Python tutorial or two.  These are
fairly basic attributes of the Python language.  If you're using
regular expressions, you'll want to be aware of how to make raw
strings to help you out.

  --Jason