'While' question

Larry Bates larry.bates at vitalEsafe.com
Fri Aug 22 01:29:34 CEST 2008

Ben Keshet wrote:
> Thanks for the reference.  I tried it with a general example and got it 
> to work - I used an index that counts up to a threshold that is set to 
> break.  It does not work though with my real code. I suspect this is 
> because I cannot really read any lines from an empty file, so the code 
> gets stuck even before I get to j=j+1:
> line = f.readline()[:-1]
>            j=0
>            while 'PRIMARY' not in line:
>                line = f.readline()[:-1]
>                j=j+1                             if j==30:
>                   break              
> Any suggestions?
> BK
> Wojtek Walczak wrote:
>> On Thu, 21 Aug 2008 18:01:25 -0400, Ben Keshet wrote:
>>> somehow. I use 'while 'word' not in line' to recognize words in the 
>>> texts. Sometimes, the files are empty, so while doesn't find 'word' 
>>> and runs forever. I have two questions:
>>> 1) how do I overcome this, and make the script skip the empty files? 
>>> (should I use another command?)
>>> 2) how do I interrupt the code without closing Python? (I have 
>>> ActivePython)
>> Try the docs first. You need to read about 'continue' and
>> 'break' statements: http://docs.python.org/tut/node6.html
>> HTH.

You might consider turning this around into something like:

for j, line in enumerate(f):
     if 'PRIMARY' in line:

     if j == 30:

IMHO this is MUCH easier to understand.


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