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From: tarjeij@ulrik.uio.no (Tarjei Jensen)
Subject: Re: CRC in Ada?
Date: 1997/03/10
Message-ID: <5g157e$pqf@ratatosk.uio.no>#1/1
X-Deja-AN: 224396643
References: <1997Mar2.220652@nova.wright.edu> <1997Mar5.131846.1@eisner>
Organization: University of Oslo, Norway
Newsgroups: comp.lang.ada
Date: 1997-03-10T00:00:00+00:00
List-Id: <comp.lang.ada>


>In article <33206340.2616@bix.com> Tom Moran <tmoran@bix.com> writes:
>
>   The original message in this thread did not say "reading a file a
>   character at a time is slow", but rather that doing it in Ada was an
>   order of magnitude slower than doing it in C, on the same OS and
>   hardware.  Since there is no other way strictly in Ada to read a file
>   which is too large for memory and whose size is a prime number, this is
>   unfortunate.  And saying Ada 95 can do it by calling a C function, is
>   less than a strong endorsement of Ada.
>

The usual explanation is that the C standard library buffers I/O while many
other languages does not have that requirement. If Ada required that the
stream I/O libraries had to support buffering then Ada would probably be as
fast as C for single character I/O.

The slowness of Ada is probably because each read triggers an system call which
reads a single character.

Good example: use Turbo Pascal under MSDOS and experiment with the buffer size
for the same program. Differences are dramatic.


Greetings,
-- 
// Tarjei T. Jensen 
//    tarjeij@ulrik.uio.no || fax +47 51664292  || voice +47 51 85 87 39
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