sum_series() 求一列数的指定个数的数和(5个数字的和)

#include <stdio.h>
#include <stdarg.h>
/*用sum_series() 求一列数的指定个数的数和(5个数字的和)*/
double sum_series(int num, ...);

int main()
{
    double s;
    s = sum_series(5, 0.5, 0.25, 0.125, 0.06254, 2.0);
    printf("Sum of series is %2.8f.\n", s);
    return 0;
}

double sum_series(int num, ...)
{
    double sum= 0.0, t;
    va_list a;
    va_start(a, num);
    for(; num; num--)
    {
        t= va_arg(a, double);
        sum= sum+ t;
    }
    va_end(a);
    return sum;
}