Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.c > #13501

Re: Deleting first N lines from a text file

Show all headers | View raw

jgharston <jgh@arcade.demon.co.uk> writes:
> Try replacing:
>>         while((c = fgetc(f)) != EOF) {
>>                 fputc(c, ftmp);
>>         }
>
> with:
>         bsize=m_free(0);
>         buff=m_alloc(bsize);
>         numread=-1;
>
>         while(numread) {
>           numread=fread(buff,1,bsize,f);
>           fwrite(buff,1,numread,ftmp);
>           }
>         m_free(buff);
>
> As with usenet tradition, completely untested.

Leaving aside the m_free and m_alloc calls, why do you assume that this
will be significantly faster than the fgetc/fputc loop?  stdio does its
own buffering.

-- 
Keith Thompson (The_Other_Keith) kst-u@mib.org  <http://www.ghoti.net/~kst>
"We must do something.  This is something.  Therefore, we must do this."
    -- Antony Jay and Jonathan Lynn, "Yes Minister"

Back to comp.lang.c | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

Deleting first N lines from a text file pozz <pozzugno@gmail.com> - 2011-11-14 16:02 -0800
  Re: Deleting first N lines from a text file Roberto Waltman <usenet@rwaltman.com> - 2011-11-14 19:21 -0500
    Re: Deleting first N lines from a text file Acid Washed China Blue Jeans <chine.bleu@yahoo.com> - 2011-11-14 16:31 -0800
      Re: Deleting first N lines from a text file blp@cs.stanford.edu (Ben Pfaff) - 2011-11-14 16:36 -0800
      Re: Deleting first N lines from a text file Roberto Waltman <usenet@rwaltman.com> - 2011-11-14 20:10 -0500
      Re: Deleting first N lines from a text file Phil Carmody <thefatphil_demunged@yahoo.co.uk> - 2011-11-16 11:04 +0200
  Re: Deleting first N lines from a text file gordonb.3hlvm@burditt.org (Gordon Burditt) - 2011-11-14 18:53 -0600
  Re: Deleting first N lines from a text file Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-11-14 22:06 -0500
    Re: Deleting first N lines from a text file Giuseppe <giuseppe.modugno@gmail.com> - 2011-11-15 16:57 -0800
      Re: Deleting first N lines from a text file Keith Thompson <kst-u@mib.org> - 2011-11-15 17:50 -0800
        Re: Deleting first N lines from a text file pozz <pozzugno@gmail.com> - 2011-11-15 23:11 -0800
          Re: Deleting first N lines from a text file jgharston <jgh@arcade.demon.co.uk> - 2011-11-16 04:11 -0800
      Re: Deleting first N lines from a text file Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-11-15 21:48 -0500
        Re: Deleting first N lines from a text file pozz <pozzugno@gmail.com> - 2011-11-15 23:14 -0800
          Re: Deleting first N lines from a text file "BartC" <bc@freeuk.com> - 2011-11-16 14:26 +0000
            Re: Deleting first N lines from a text file Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-11-16 21:32 -0500
              Re: Deleting first N lines from a text file Ian Collins <ian-news@hotmail.com> - 2011-11-17 15:43 +1300
                Re: Deleting first N lines from a text file "BartC" <bc@freeuk.com> - 2011-11-17 10:35 +0000
                Re: Deleting first N lines from a text file Dr Nick <3-nospam@temporary-address.org.uk> - 2011-12-16 07:05 +0000
              Re: Deleting first N lines from a text file Robert Wessel <robertwessel2@yahoo.com> - 2011-11-16 22:46 -0600
      Re: Deleting first N lines from a text file gordonb.pa5u0@burditt.org (Gordon Burditt) - 2011-11-16 16:28 -0600
        Re: Deleting first N lines from a text file Kaz Kylheku <kaz@kylheku.com> - 2011-11-16 22:53 +0000
          Re: Deleting first N lines from a text file gordonb.z5i2o@burditt.org (Gordon Burditt) - 2011-11-16 18:34 -0600
  Re: Deleting first N lines from a text file jacob navia <jacob@spamsink.net> - 2011-11-15 12:48 +0100
    Re: Deleting first N lines from a text file "-.-" <none@none.none> - 2011-11-16 14:01 +0100
      Re: Deleting first N lines from a text file jacob navia <jacob@spamsink.net> - 2011-11-16 14:44 +0100
        Re: Deleting first N lines from a text file tom st denis <tom@iahu.ca> - 2011-11-17 10:43 -0800
          Re: Deleting first N lines from a text file jt@toerring.de (Jens Thoms Toerring) - 2011-11-18 23:12 +0000
  Re: Deleting first N lines from a text file jgharston <jgh@arcade.demon.co.uk> - 2011-11-16 06:42 -0800
    Re: Deleting first N lines from a text file jgharston <jgh@arcade.demon.co.uk> - 2011-11-16 07:43 -0800
    Re: Deleting first N lines from a text file Keith Thompson <kst-u@mib.org> - 2011-11-16 11:13 -0800
      Re: Deleting first N lines from a text file jgharston <jgh@arcade.demon.co.uk> - 2011-11-16 13:50 -0800

csiph-web