On Tuesday 08 September 2009 09:39:40 pm you wrote:
> Hi again...
>
> int fd; /* RS232 serial link */
> int fdp; /* file descriptor for a regular file */
> struct stat stat;
> size_t bytes = 0;
> void *buffer; /* buffer, will be allocated */
> ...
> while (bytes < stat.st_size) {
> ret = read(fdp, buffer + bytes, stat.st_size - bytes);
> if (ret == -1) {
> perror("read");
> return -1;
> }
> ret = write(fd, buffer + bytes, ret);
> if (ret == -1) {
> perror("write");
> return -1;
> }
> bytes += ret;
> progress = (int) (bytes * 100) / stat.st_size;
> printf("\rcompleted: %i%%", progress); /* NO OUTPUT, UNTIL LOOP
> ENDED */ fflush(stdout);
> }
> ...
>
> Then i see printf() never output the message until the loop has ended...
> 'fdp' is a file descriptor to a local file, i send it through a serial
> connection (RS232),
> i use a serial connection so i can practice Linux's File I/O operation
> in real world ;p
>
> the receiver can output the progress's message, but the sender (the
> above code) could not...
> this is the receiver codes:
>
> ...
> while (bytes < size) {
> ret = read(fd, buffer + bytes, size - bytes);
> if (ret == -1) {
> perror("read");
> return -1;
> }
> ret = write(fdp, buffer + bytes, ret);
> if (ret == -1) {
> perror("write");
> return -1;
> }
> bytes += ret;
>
> progress = (int) (bytes * 100) / size;
> printf("\rcompleted: %i%%", progress); /* HAS OUTPUT */
> fflush(stdout);
> }
> ...
>
> On Tue, Sep 8, 2009 at 8:49 PM, Glynn Clements<glynn@xxxxxxxxxxxxxxxxxx>
wrote:
> > Tim Walberg wrote:
> >> Maybe you want "(bytes * 100) / size"?
> >
> > However, if int and size_t are 32-bit, that will overflow at around
> > 20 or 40 MB (20 for signed, 40 for unsigned), which isn't really all
> > that much. Converting to either double or long long might be wise,
> > i.e.
> >
> > percent = (int)(bytes * 100.0) / size;
> > or:
> > percent = (int)(bytes * 100LL) / size;
> >
> > --
> > Glynn Clements <glynn@xxxxxxxxxxxxxxxxxx>
>
> --
> To unsubscribe from this list: send the line "unsubscribe
> linux-c-programming" in the body of a message to majordomo@xxxxxxxxxxxxxxx
> More majordomo info at http://vger.kernel.org/majordomo-info.html
Wow. I feel silly. Ignore my previous message. It's late here and I missed the
fflush().
--
To unsubscribe from this list: send the line "unsubscribe linux-c-programming" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
