Hi jcl,
man what a mess. I never had read that thingy about the \n. Thanks. Now I've got the output! :-)
The manual clearly states this:
For printing on a new line in the message window, begin the text with the linefeed symbol "\n". Otherwise printf appends the text to the end of the current line.
So I haven't read the manual good enough. My fault. I programmed in other C languages and there you can set the \n at the end of the line...