(K&R, §A10.1) The C compiler can accept an unnamed argument in a function definition. For example:
void f(int ) {} /* OK, if ANSI Strict is off */
void f(int i) {} /* ALWAYS OK */To turn this feature on, turn off the ANSI Strict setting in the C/C++ Language Panel. If the ANSI Strict setting is on, then this extension to standard C is disabled.