[Tutor] file io and the open() function

[Kirk Bailey]

Indeed it helps. Thankyou.

Brimstone has been posted in a seperate post.

It is said that even assembly has the Buddha nature, but try not to
program in cobol if you can possibly help it.

Years ago I converted the TAO of programming from plain text to a
executable Ebooklet. Now I think I must do this for html.




Danny Yoo wrote:
> 
> On Mon, 19 Nov 2001, Kirk Bailey wrote:
> 
> > A novice approaches the masters and asks:
> >
> > I want to open a pair of files, read from one, wtite it to another,
> > appeding data.
> 
> Thus spake the master programmer:
> 
> ``When you have learned to snatch the error code from the trap frame, it
> will be time for you to leave.''
> 
>     http://www.canonical.org/~kragen/tao-of-programming.html
> 
> *grin*
> 
> > I wanted to craft this tool to use variables for the 2 files and the
> > domain name, so it would be a useful general purpose tool for use by
> > others. Alas, when it tries to open a file with a variable providing
> > the namer, it halts and catches fire, barfing evilgrams at me.
> 
> Can you show us what sort of brimstone belches from the beast... err...
> that is, can you show us an error message?
> 
> > Also, as I cannot tell in advance howm any entries will be in the
> > source file, this thing has to work in a loop until the source file is
> > exausted, then close both files. How do I detet the endoffile and end
> > politely, instead of running off the end of the thing and tripping an
> > error?
> 
> At the very end of a file, readline() will return the empty string
> "".  You can use this to your advantage:
> 
> ###
> while 1:
>     line = file.readline()
>     if not line: break
>     ...
> ###
> 
> Alternatively, you can avoid the problem altogether by grabbing your file
> as a list of lines, by using readlines():
> 
> ###
> for line in file.readlines():         ## Also look in the docs about
>                                       ## xreadlines(), which is better
>                                       ## for long files.
>    ...
> ###
> 
> For more information about these file methods, you can take a look at:
> 
>     http://www.python.org/doc/lib/bltin-file-objects.html
> 
> Hope this helps!

-- 
Respectfully,
             -Kirk D Bailey (C)2001
              Addme! icq #27840081
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