varargs.c

来自「经典书籍：C Primer Plus(第五版)中文版和源代码 本书全面讲述了C」· C语言 代码 · 共 33 行

//varargs.c -- use variable number of arguments
#include <stdio.h>
#include <stdarg.h>
double sum(int, ...);

int main(void)
{
    double s,t;

    s = sum(3, 1.1, 2.5, 13.3);
    t = sum(6, 1.1, 2.1, 13.1, 4.1, 5.1, 6.1);
    printf("return value for "
           "sum(3, 1.1, 2.5, 13.3):                %g\n", s);
    printf("return value for "
           "sum(6, 1.1, 2.1, 13.1, 4.1, 5.1, 6.1): %g\n", t);
 
    return 0;
}

double sum(int lim,...)
{
    va_list ap;                   // declare object to hold arguments
    double tot = 0;
    int i;

    va_start(ap, lim);            // initialize ap to argument list
    for (i = 0; i < lim; i++)
       tot += va_arg(ap, double); // access each item in argument list
    va_end(ap);                   // clean up
 
    return tot;
}