How can i compare a string which is non null and empty

[Steven D'Aprano]

On Mon, 02 Apr 2007 01:35:17 +0200, Georg Brandl wrote:

> Plissken.s at gmail.com schrieb:
>> Hi,
>> 
>> how can i compare a string which is non null and empty?
>> 
>> 
>> i look thru the string methods here, but cant find one which does it?
>> 
>> http://docs.python.org/lib/string-methods.html#string-methods
>> 
>> In java,I do this:
>> if (str != null) && (!str.equals("")) ....
>> 
>> how can i do that in python?
> 
> Strings cannot be "null" in Python.
> 
> If you want to check if a string is not empty, use "if str".


I tried that, and I get something unexpected.

>>> if str:
...     print "What's going on here?"
... else:
...     print "An empty string."
...
What's going on here?


 
> This also includes the case that "str" may not only be an empty
> string, but also None.

What about the case where str hasn't been shadowed and is a built-in type?

>>> str
<type 'str'>




-- 
Steven D'Aprano