Using standard I/O on pipes?

[Gabriel Ambuehl]

Hi,
I'm running into trouble using stdio on pipes. Basically, my app
redirects the stdout to a pipe and then execs a filter which should
be able to printf() and all other means that write to stdout but when
I run the code, it will only transmit data that I write directly with
write() systemcalls. I'm thinking this should work (else I couldn't
use printf() on stdout pipes in a shell neither) but maybe I'm
overlooking something.