At 1:38 PM +1100 2/3/09, Jacob Rhoden wrote:
On 3/02/2009 8:41 AM, Kenneth Bruno II wrote:
I am wondering what the best way to read a text file, line by
line, when the file size is much larger than available memory.
For very large files you probably want to use NSFileHandle. With
the method readDataOfLength: you can read the file in chunks and
then parse through for the line endings.
I also find the non existence of a readLine type mechanism quite
strange. Either way, this has given me enough to go on so thanks for
the help!
I can just read in large blocks, read each line within the large
block, then use the index of the last line ending to fetch the next
large block.
Umm, unless I'm totally missing something, what's wrong with fopen()
and fgets(), possibly followed with [NSString stringWithCString] on
each line?
fgets() returns the EOL character, so you can detect lines that don't
fit in the buffer. I'll leave handling this case as an exercise.
I'm guessing that Cocoa would assume access to the standard C library
and doesn't bother duplicating functionality.
At 8:02 PM -0800 2/2/09, Peter Duniho wrote:
For line delimiters, it's almost always going to be \n or \r\n.
It's simple enough to treat either as a line-break, or to ask the
user if for some reason \n is a valid character within a line of a
\r\n-delimited file (but that's very rare). Certainly, line-breaks
are a lot easier to deal with in a general, reliable way than
character encodings. :)
If you're doing your own line-end detection, I've used the following algorithm:
1) If you see either \r or \n you're at a line end.
2) If the next character is the other, skip it
This handles \r, \n, \r\n, \n\r, plus gracefully handles files with
mangled line endings with the only possible failure of eating or
emitting a stray blank line at the point were line endings change in
the file.
(This thread seems to be off in the weeds)
Cheers,
-Steve
_______________________________________________
Cocoa-dev mailing list (Cocoa-dev@lists.apple.com)
Please do not post admin requests or moderator comments to the list.
Contact the moderators at cocoa-dev-admins(at)lists.apple.com
Help/Unsubscribe/Update your Subscription:
http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com
This email sent to arch...@mail-archive.com
