Re: Read lines from very large text file
Re: Read lines from very large text file
- Subject: Re: Read lines from very large text file
- From: Peter Duniho <email@hidden>
- Date: Mon, 2 Feb 2009 20:02:39 -0800
On Feb 2, 2009, at 7:50 PM, Joar Wingfors wrote:
How do you know what delimiter string to use? Another thing that
you'd have to determine, guess or be told, right? In general I would
guess that it in this case almost always would be impossible and /
or inappropriate to attempt to determine either of these two, and
that you would have to simply default to something reasonable.
UTF-8 covers most files, due to being backward-compatible with ASCII.
Occasionally, ISO-8859-1 is a decent guess, due to its wide-spread
usage (and is also compatible with ASCII).
But there's no general-purpose way to know for sure the character
encoding if _all_ you have is a plain old text file. You always
should provide a way for the user to specify character encoding, where
it's not known for sure what the encoding is.
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. :)
[...] In any case, if you think that Cocoa should provide an
enumerator that given either NSData or a path / NSURL, and provided
the appropriate encoding, returns individual lines as NSStrings,
please make sure that you file a radar and ask for it.
I will indeed. It's unfortunate that the Radar system doesn't provide
a way to view other people's submissions and to validate, vote,
provide work-arounds for, or otherwise comment on them (รก la
Microsoft's Connect web site). Making each person submit their own
report is tedious, to say the least (thinking of Michael Ash's
NSOperationQueue issue here :) ).
Pete_______________________________________________
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