Help writelines

Dave Angel d at davea.name
Fri Feb 3 21:56:29 CET 2012


On 02/03/2012 03:27 PM, Anatoli Hristov wrote:
> Hi everyone,
>
> I`m totaly new in python and trying to figure out - how to write a list to
> a file with a newline at the end of each object.
> I tried alot of combinations :) like:
> users = ['toli','didi']
> fob=open('c:/Python27/Toli/username','w')
> fob.writelines(users) + '%s\N'
> fob.close()
>   or fob.writelines('\N' % users)
> or fob.writelines('%s\N' % users)
> but nothing of dose works...
>
> Could you help me find out the right syntaxes?
>
> Thanks
>
mylist.writelines() is a shorthand for a loop of writes, once per list 
item.  It does not append a newline, since if the list had come from 
readlines(), it would already have the linefeed on each line.

So you have a few choices.  You could add a newline to each list item 
before issuing the writelines(), or write your own loop.  I vote for 
writing your own loop, since there may be other things you want to 
change on each line.

1)
   users = [item+"\n" for item in users]        # add a newline to each item

2)
   for line in users:
        fob.write(line + "\n")
   fob.close()

There are other possibilities, such as
     contents = "\n".join(mylist)      #make a single string out of it
     fob.write(contents + "\n")        #note we had to add one at the 
very end,
            #because join just puts the separator between items, not 
after them.




-- 

DaveA




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