An ellipsis is used to represent a variable number of parameters to a function. For example:
void format(const char* fmt, ...)
The above function in C could then be called with different types and numbers of parameters such as:
format("%d-%d-%d", 2010, 9, 25);
and
format("product: %s, price: %f", "HDD", 450.90);
C99 introduced Variadic macros which also makes use of ellipsis.
