Path: utzoo!censor!geac!yunexus!xrtll!silver
From: silver@xrtll.uucp (Hi Ho Silver)
Newsgroups: comp.sys.ibm.pc
Subject: Re: File concatenation using Microsoft C under MS-DOS?
Message-ID: <1990Jun10.151036.25368@xrtll.uucp>
Date: 10 Jun 90 15:10:36 GMT
References: <4891@druco.ATT.COM>
Reply-To: silver@.UUCP (PUT YOUR NAME HERE)
Organization: Not around here, pal!
Lines: 37

In article <4891@druco.ATT.COM> gibbons@druco.ATT.COM (GibbonsT) writes:
$  What's the quickest way to concatenate one large file (~100K) to 
$  another using Microsoft C under MS_DOS?  Write now I'm just opening 
$  the two files and reading from one and append to the other, but it
$  is rather slow.  The DOS "copy" command can do this much more 
$  quickly using "copy A + B" but I can't figure out how to run
$  "copy" from a C program.  I've tried calling "copy" with a 
$  spawnl() command but that didn't work so i made a batch file
$  that called copy and then tried to spawnl() the batch file,
$  but that didn't work.  So, any suggestions? Any I overlooking
$  something extremely obvious?

   As far as trying to invoke a child process, you can't use spawn for
what you're trying:

- you can't spawn copy since it's ain internal command and spawn will
  only run .com and .exe commands

- you can't spawn a batch file since it requires command.com

   The ways around these are to use tye system() call, which passed
your argument to a copy of the command processor (basically, it comes up
with the equivalent of a spawn to "command /c your-commands-here").

   I assume your C solution involved simply reading the files one
character at a time.  This is not a good way to do it, since there's a
certain amount of overhead in each read you do and it adds up like crazy.
The way to do it is to find the commands in your implementation of C that
allow you to read and write large blocks at a time.  If memory serves,
the Turbo C calls are blockread() and blockwrite(), which will read and
write as much (up to 64K) of a file as you want them to.  This speeds
things up tremendously.  I'm sure MSC has equivalent calls.
-- 
   /Nikebo \ Nikebo says "Nikebo knows how to post.  Just do it."\silver@xrtll/
  /---------\_____________________________________________________\----------/
 /yunexus!xrtll!silver (L, not 1)\ Hi Ho Silver \   just silver for short   /
/Silver:  Ever Searching for SNTF \  Life sucks. \  someone buy me a BEER! /