[LC++]file copying

[Jan Pfeifer]

hi Larry,

copying the file byte by byte incurs in a high overhead (one function
call per byte). Try using a bigger buffer. Check attached code.

:)

jan

ps.: i did some measuring with the code, and it still takes 1.5 the time
/bin/cp takes to copy. Anyone knows how /bin/cp does this faster ? I
would guess it somehow manages to avoid a buffer copying, maybe using
memory mapped files ...

On Wed, 2004-01-28 at 00:57, larry wrote:
> I have a problem related to the speed of copying files in C++ on
> linux. I need to automate a process to copy files from one directory
> to another for media management. Anyway, the following code is what I
> have been using and it is not nearly fast enough. The entire focus of
> this application is speed. In fact in Windows, I am getting at least 5
> times the speed from a VB app that I am using. I know I must be doing
> something wrong. I am compiling on a one processor machine and moving
> it to the test equipment which has four processors and 4 gigs or RAM.
> I wonder should I compile it there to see if it runs better or is
> there a better method for copying files from one directory to another.
> The file system is Reiserfs on a gentoo installation. The machine that
> I am compiling on is ext3 on Redhat.
> 
> IPFile = fopen("/home/this.jpg","r");
> OPFile = fopen("/mediafiles/this.jpg","w");
> while ((c = fgetc(IPFile)) != EOF)
> {
> fputc(c, OPFile);
> }
> fclose(IPFile);
> fclose(OPFile);
> 
> Anyway, I am at a loss. There has to be a better method than this.
> Thanks.
> 
> ---
> Larry Lines
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