C语言实例70：可变数目变元

#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>

double sum_series(int num, ...);

int main(int argc, char *argv[])
{
    double d;
    d = sum_series(4, 0.5, 0.25, 0.125, 0.6254);
    printf("Sum of series is %f.\n", d);


    system("pause");
    return 0;
}

double sum_series(int num, ...)
{
    double sum = 0.0, t;
    va_list argptr;

    va_start(argptr, num);

    for(; num; num--)
    {
        t = va_arg(argptr, double);
        sum = sum + t;

    }

    va_end(argptr);
    return sum;
}