hi,
if i use getc to read from file , can i assume it to be slower than fgets or fread or it does not matter? thanks a million..
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Hello zizi21,
It may not be significantly sloerw but it is not going to be faster.
I/O operations are typically buffered. So even though you fetch a char, system would fetch an entire disk block. Further requests would be satisfied from this block. So the extra time spent would be in calls and not I/O.
This is implementation dependent and not standard but should be fairly common behavior.
Regards,
sunnycoder
>> can i assume it to be slower than fgets or fread
Well they do different things to it's a bit like comparing apples and oranges but I don't think you van safely assume anything since nothing is defined in the standards docs regarding performance. If performance is a critical issue you should use a profiling tool to determine which, on the platforms you need to support, is better performant.
>> or it does not matter
That depends upon your requirements :)
>> can i assume it to be slower than fgets or fread or it does not matter?
Ah, I misread. I thought you were talking about fgetc.
If you mean that you read one character at a time in a loop, as opposed to reading all characters at the same time using fgets, then yes, it will be slower, since you have the overhead of the loop.
>> Either ways, it is never going to be equivalent.
If you are referring to my first post which compared getc and fgetc, then yes they are equivalent as per the standard ;)
"The getc function is equivalent to fgetc, except that if it is implemented as a macro, it
may evaluate stream more than once, so the argument should never be an expression
with side effects."
>> What you quoted is functionality and not speed.
I see no reason for getc and fgetc having different performance on any system I know. But yes, technically you are right :)
Anyway, that's beside the topic, which is about getc compared to fgets ... zizi21, did you notice that you accepted a reply that doesn't answer your question ?
>> Please leave your specific (Comment ID) recommendations below my post
My suggestion is thus...
PAQ: http:#22014489 sunnycoder
PAQ: http:#22014492 evilrix
PAQ: http:#22014496 infinity08
As all three provide a reasonable answer for the OP to consider.
>> Please leave your specific (Comment ID) recommendations below my post
My 2c.
There is a subtle problem here. Although profiling should ALWAYS be used to determine the correct processes to optimise, asker wanted to 'assume' not 'determine' or 'measure'. In this respect, sadly, the suggestion to use a profiler should be judged off-topic.
My suggestion is thus...
SPLIT:
http:#22014489 sunnycoder
http:#22014496 infinity08
In my opinion ER's point that performance should be optimized through careful profiling, NOT assumptions, is actually more valuable for the PAQ than the answers provided. Unfortunately only the assumption was in question and was therefore covered by the other two answers.
Paul <ZA>
Business Accounts
Answer for Membership
by: Infinity08Posted on 2008-07-16 at 02:56:55ID: 22014486
It's equivalent. Usually, getc is even implemented as a macro that uses fgetc.