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On 05/02/2009, at 7:44 AM, Adam Glauser wrote:
I have a routine which reads a stream file byte by byte looking for
record start and end delimiters. I have implemented my own buffering.
Now I'm looking at trying to separate the buffered reading from the
actual parsing so that I can handle records without start
delimiters, as
well as delimiters of arbitrary length.
I presume this is using the Unix APIs open, read, close?
It should be relatively easy to modify my current buffering code to
work
with different delimiters, but I wonder if I'd be better off just
using
the _C_IFS_(fopen,fclose,fread) functions.
These functions automatically perform buffering for you (which is
probably why you're asking about them). You can set the buffering to
fully-buffered, line-buffered, or no buffering.
Note that line-buffering only works on new-line and not an arbitrary
end-of-line delimiter.
One can presume these APIs will perform faster than the Unix APIs due
to the buffering but whether they're faster than your own buffering
routines can only be answered by empirical testing.
What would you choose and why?
Depends entirely on my needs, I've used open to get more control than
fopen provides, then used fdopen to associate a stream with the file
descriptor, then used the fxxxx functions to get the OS to buffer for
me.
Other times I do my own buffering--especially with socket data.
Whether you do your own buffering or use the OS buffering you'll
still have to deal with incomplete data where you have part of the
desired data in the buffer but the buffer is full. Dealing with this
situation may be easier when you control the buffering.
Regards,
Simon Coulter.
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