[C and pointer] indefinite Parameters

I. Variable Parameter instance [html] # include "stdio. h "/* function parameters are accessed in the form of Data Structure" stack ", from right to left. eg: */void fun (int ,...) {int * temp = & a; temp ++; int I; for (I = 0; I <a; ++ I) {printf ("% d \ n ", * temp); temp ++ ;}} int main () {int a = 1; int B = 2; int c = 3; int d = 4; fun (4, a, B, c, d); return 0;} 2. Use va_start to direct argp to the first optional parameter in va_list. Va_arg returns the current parameter in the parameter list and points argp to the next parameter in the parameter list. Va_end clears the argp pointer to NULL. The function can traverse these parameters multiple times, but all parameters must start with va_start and end with va_end [html # include <stdio. h> # include <string. h> # include <stdarg. h> int demo (char * msg ,...) {va_list argp; int argno = 0; char * para; va_start (argp, msg); while (1) {para = va_arg (argp, char *); if (strcmp (para, "") = 0) break; printf ("Parameter # % d is: % s \ n", argno, para); argno ++ ;} va_end (argp); return 0;} int main (void) {www.2cto.com demo ("DEMO ", "This", "is", "a", "demo! "," ");} 3. Use [html] # include <stdio. h> # include <string. h> # include <stdarg. h> void myprintf (char * fmt ,...) {char * pArg = NULL; char c; pArg = (char *) & fmt; pArg + = sizeof (fmt); do {// judge each character, until the end of the entire statement c = * fmt; if (c! = '%') Putchar (c); else {switch (* ++ fmt) {case 'D': printf ("% d", * (int *) pArg); break;} pArg + = sizeof (int);} + + fmt;} while (* fmt! = '\ 0'); pArg = NULL; // va_end} int main (void) {myprintf ("the fist: % d \ nthe secound: % d \ n ", 1, 2);} 4. For details, there is an stdarg in the include of VC ++ 6.0. the h header file has the following macro definitions: # define _ INTSIZEOF (n) (sizeof (n) + sizeof (int)-1 )&~ (Sizeof (int)-1) # define va_start (ap, v) (ap = (va_list) & v + _ INTSIZEOF (v )) // The first optional parameter address # define va_arg (ap, t) (* (t *) (ap + = _ INTSIZEOF (t)-_ INTSIZEOF (t ))) // next parameter address # define va_end (ap) (ap = (va_list) 0) // set the pointer to invalid [html] # include <iostream> # include <stdarg. h> const int N = 5; using namespace std; void Stdarg (int a1 ,...) {va_list argp; int I; int ary [N]; va_start (argp, a1); ary [0] = a1; for (I = 1; I <N; I ++) ary [I] = va_arg (argp, int); va_end (argp); for (I = 0; I <N; I ++) cout <ary [I] <endl;} void main () {Stdarg (5, 12, 64, 34, 23 );}