1 int printf(const char *format, ...);
2 int scanf(const char *format, ...);

1 void func(char *fmt, ...){
2       va_list ap;
3       va_start(ap, fmt);
4       va_arg(ap, int);
5       va_end(va);      
6 }

1 #define _INTSIZEOF(n) ((sizeof(n)+sizeof(int)-1)&~(sizeof(int) - 1) )
2 #define va_start(ap,v) ( ap = (va_list)&v + _INTSIZEOF(v) ) //第一个可选参数地址
3 #define va_arg(ap,t) ( *(t *)((ap += _INTSIZEOF(t)) - _INTSIZEOF(t)) ) //下一个参数的值
4 #define va_end(ap) ( ap = (va_list)0 ) // 将指针置为无效

 1 void setinsert(symset s, int elem)
 2 {
 3     snode* p = s;
 4     snode* q;
 5 
 6     while (p->next && p->next->elem < elem)
 7     {
 8         p = p->next;
 9     }
10     
11     q = (snode*) malloc(sizeof(snode));
12     q->elem = elem;
13     q->next = p->next;
14     p->next = q;
15 } // setinsert
16 
17 symset createset(int elem, .../* SYM_NULL */)
18 {
19     va_list list;
20     symset s;
21 
22     s = (snode*) malloc(sizeof(snode));
23     s->next = NULL;
24 
25     va_start(list, elem);
26     while (elem)
27     {
28         setinsert(s, elem);
29         elem = va_arg(list, int);
30     }
31     va_end(list);
32     return s;
33 } // createset