Calling a variadic function with an unknown number of parameters

Question

Say I have a function that takes a variable number of parameters: I want to call this function from somewhere else, building the list of parameters, but without knowing in a

Answer 1

When I've need to do something like this, I got it to work with a "switch-fan".

switch( n ){
case 1:  foo(0);     break;
case 2:  foo(0,0);   break;
case 3:  foo(0,0,0); break;
}