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Re: skipping bytes

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In article <4e25d86a$0$1975$bbae4d71@news.suddenlink.net>,
Bill Cunningham <nospam@nspam.invalid> wrote:
> blmblm@myrealbox.com wrote:
> > In article <4e24a90b$0$8602$bbae4d71@news.suddenlink.net>,
> > Bill Cunningham <nospam@nspam.invalid> wrote:
> >> John Gordon wrote:
> >>> In <4e24a281$0$1929$bbae4d71@news.suddenlink.net> "Bill Cunningham"
> >>> <nospam@nspam.invalid> writes:
> >>>
> >>>>     I want to take a 700MB file and skip evey 200MB, so I thought
> >>>> of this.
> >>>
> >>> You mean you want to copy the 700MB file to another file, omitting
> >>> 200MB chunks?
> >>>
> >>>> long * space=malloc(sizeof(long)*500000);
> >>>
> >>> There's no need to allocate that much space for a simple copy
> >>> operation.
> >>> You can copy, say, 8K or 16K at a time without allocating a huge
> >>> buffer.
> >>
> >>     I actually wanted to do something a little more difficult than
> >> just copy the file. Every 200MB I want to save in a buffer about 8
> >> bytes of data and exchange 0x0000 for it. It doesn't have to be
> >> every 200M but it's such a large file I thought of 200MB. Not using
> >> malloc() makes things so much easier. It doesn't have to be exactly
> >> 8 bytes it could be 32. The important thing is to correctly store
> >> the data read and save it correctly so it could be put back.
> >
> > Do you have some end goal in mind, or are you doing this because it
> > somehow strikes you as an interesting or entertaining problem in its
> > own right?  I can't make much sense of the above description and am
> > (mildly) curious.
> 
>     Please don't say "don't reinvent the wheel" it's all been done. 
> Everything is a learning experience. By punching "holes" in a file you make 
> it unreadable. By saving that information and reinserting it it becomes 
> readable again.

Oh!  Okay, well, that's not a task I'd have set myself, but this
description is *almost* enough for me to imagine what the code
might be like, and I guess I can sort of understand how it might
seem like an interesting problem.  (Depending on what kind of file
it is, just replacing some of the data might or might not make it
totally unreadable.  But that may not matter to you.)

One question you might ask yourself is where you're going to
save the data you overwrite and want to put back later -- will
it go in some separate file, or in some predetermined place in
the original, or what?  

-- 
B. L. Massingill
ObDisclaimer:  I don't speak for my employers; they return the favor.

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Thread

skipping bytes "Bill Cunningham" <nospam@nspam.invalid> - 2011-07-19 05:15 -0400
  Re: skipping bytes John Gordon <gordon@panix.com> - 2011-07-18 21:35 +0000
    Re: skipping bytes "Bill Cunningham" <nospam@nspam.invalid> - 2011-07-19 05:43 -0400
      Re: skipping bytes blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-07-19 17:27 +0000
        Re: skipping bytes Chad <cdalten@gmail.com> - 2011-07-19 12:09 -0700
          Re: skipping bytes blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-07-19 21:34 +0000
        Re: skipping bytes "Bill Cunningham" <nospam@nspam.invalid> - 2011-07-20 03:17 -0400
          Re: skipping bytes blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-07-19 21:35 +0000
            Re: skipping bytes "Bill Cunningham" <nospam@nspam.invalid> - 2011-07-20 07:01 -0400
            Re: skipping bytes "Bill Cunningham" <nospam@nspam.invalid> - 2011-07-22 11:25 -0400
  Re: skipping bytes Ian Collins <ian-news@hotmail.com> - 2011-07-19 09:42 +1200

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