These are called Variadic functions. Wikipedia lists example code for C++.
To portably implement variadic
functions in the C programming
language, the standard stdarg.h header
file should be used. The older
varargs.h header has been deprecated
in favor of stdarg.h. In C++, the
header filecstdarg
should be used.To create a variadic function, an
ellipsis (...
) must be placed at the
end of a parameter list. Inside the
body of the function, a variable of
typeva_list
must be defined. Then the
macrosva_start(va_list, last fixed
,
param)va_arg(va_list, cast type)
,
va_end(va_list)
can be used. For
example:
#include <stdarg.h>
double average(int count, ...)
{
va_list ap;
int j;
double tot = 0;
va_start(ap, count); //Requires the last fixed parameter (to get the address)
for(j=0; j<count; j++)
tot+=va_arg(ap, double); //Requires the type to cast to. Increments ap to the next argument.
va_end(ap);
return tot/count;
}