Disabling localisation for an app

["Søren Hauberg" <hauberg gmail com>]

Hi,
 I'm working on a GUI in a fairly large project, that (amongst other
things) write numeric data to a file that gnuplot will read. What this
boils down to is that I need

 printf ("%f", 1.7);

to give me "1.70000". However, if I include

 Gtk::Main kit(argc, argv);

in my application, the formating of numbers begin to depend on the
value of the $LANG environment variable. Specifically, if I set
LANG=da_DK.UTF-8 (default on my system), then the above-mentioned
printf statement gives "1,70000" (with a comma instead of a dot). How
can I (from within my application) enforce that this doesn't happen?

Thanks,
Søren