Testing for Null?

Chris cwitts at gmail.com
Sun Jun 29 16:03:34 CEST 2008


On Jun 29, 3:12 am, c0mrade <jacksinglet... at gmail.com> wrote:
> Try something like this...
>
> list = ['lkdfjsldk', None, '', '0', 'slfkjsdlfj', 'lsdgjdlfg', False, True]
> for n, it in enumerate(list):
>     if not it: print 'Error on this definition'
>     else: print '%d. %s' % (n+1, it)
>
> Results:
> 1. lkdfjsldk
> Error on this definition
> Error on this definition
> 4. 0
> 5. slfkjsdlfj
> 6. lsdgjdlfg
> Error on this definition
> 8. True
>
>
>
> Alexnb wrote:
>
> > I am having a problem with a list value that is empty. I have a list of
> > definitions called mainList. the 5th value in the list doesn't have
> > anything
> > in it. In this case, the values are definitions; also, in this case just
> > the
> > word cheese is defined. Here is my output to the console:
>
> > 5.   a sprawling,weedy plant having small lavender or white flowers and
> > round, flat, segmented fruits thought to resemble little wheels of cheese.
> > 6.
> > 7.  an ingot or billet made into a convex, circular form by blows at the
> > ends.
>
> > I've made it so where the numbers, the period, and two spaces follow that,
> > then the definition. However, as you can see in 6, there is nothing. Here
> > is
> > the code to print all this:
>
> > n=0
>
> > for x in mainList:
> >     if mainList[n] == "":
> >         print "Error on this definition"
> >     else:
> >         print str(n+1)+".  "+str(mainList[n])
> >     n=n+1
>
> > Now the two "" is where I need to figure out if it is empty. What is up
> > right now doesn't work; or at least doesn't give the desired result. So I
> > need to know how to write the if statement to make it work. This should be
> > simple, but I just don't know how to do it, never had this problem before.
>
> > --
> >http://mail.python.org/mailman/listinfo/python-list
>
> --
> View this message in context:http://www.nabble.com/Testing-for-Null--tp18175738p18176481.html
> Sent from the Python - python-list mailing list archive at Nabble.com.

myList = ['lkdfjsldk', None, '', '0', 'slfkjsdlfj', 'lsdgjdlfg',
False, True]
['%s\t%s'%((i+1),element) if element else '%s\tError on this
definition'%(i+1) for i,element in enumerate(myList)]



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