asked on
IO Buffering...
I have a question on I/O buffering, can somebody help me out:
int main() {
int c;
printf("Hello World from PID=%d.",getpid());
sleep(10);
printf("Hello Again, World! from PID=%d.\n",getpid());
return 0;
}
the above program sleeps for 10 sec and then print out's the printf's.
Whereas, the one below print's out the statement before new line and sleeps for
10 seconds. I want to understand why is that ?
#include <stdio.h>
int main() {
int c;
printf("Hello World from PID=%d.\n",getpid());
sleep(10);
printf("Hello Again, World! from PID=%d.\n",getpid());
return 0;
}
Thanks
int main() {
int c;
printf("Hello World from PID=%d.",getpid());
sleep(10);
printf("Hello Again, World! from PID=%d.\n",getpid());
return 0;
}
the above program sleeps for 10 sec and then print out's the printf's.
Whereas, the one below print's out the statement before new line and sleeps for
10 seconds. I want to understand why is that ?
#include <stdio.h>
int main() {
int c;
printf("Hello World from PID=%d.\n",getpid());
sleep(10);
printf("Hello Again, World! from PID=%d.\n",getpid());
return 0;
}
Thanks
CLinux OS Dev
Last Comment
Duncan Roe
Console output (to a screen) is usually line-buffered, meaning that a line is output when you finish it, meaning that the "\n" is the key here. Note that this is usually not true when redirecting output into a file - you should fflush(stdout) if you want to see data appearing in that file immediately, regardless of newlines.
By the way, it's all platform-dependent too. I just tested it in Windows and it prints the first line right away regardless of flushing. On Linux, it prints it only if there is a newline or if I fflush(stdout) after the first printf().
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