1013-----C语言----------几个va_宏函数的使用

#include "apue.h"
#include <errno.h>		/* for definition of errno */
#include <stdarg.h>		/* ISO C variable aruments */

static void	err_doit(int, int, const char *, va_list);

/*
 * Nonfatal error related to a system call.
 * Print a message and return.
 */
void
err_ret(const char *fmt, ...)
{
	va_list		ap;

	va_start(ap, fmt);
	err_doit(1, errno, fmt, ap);
	va_end(ap);
}

/*
 * Fatal error related to a system call.
 * Print a message and terminate.
 */
void
err_sys(const char *fmt, ...)
{
	va_list		ap;

	va_start(ap, fmt);
	err_doit(1, errno, fmt, ap);
	va_end(ap);
	exit(1);
}

/*
 * Fatal error unrelated to a system call.
 * Error code passed as explict parameter.
 * Print a message and terminate.
 */
void
err_exit(int error, const char *fmt, ...)
{
	va_list		ap;

	va_start(ap, fmt);
	err_doit(1, error, fmt, ap);
	va_end(ap);
	exit(1);
}

/*
 * Fatal error related to a system call.
 * Print a message, dump core, and terminate.
 */
void
err_dump(const char *fmt, ...)
{
	va_list		ap;

	va_start(ap, fmt);
	err_doit(1, errno, fmt, ap);
	va_end(ap);
	abort();		/* dump core and terminate */
	exit(1);		/* shouldn‘t get here */
}

/*
 * Nonfatal error unrelated to a system call.
 * Print a message and return.
 */
void
err_msg(const char *fmt, ...)
{
	va_list		ap;

	va_start(ap, fmt);
	err_doit(0, 0, fmt, ap);
	va_end(ap);
}

/*
 * Fatal error unrelated to a system call.
 * Print a message and terminate.
 */
void
err_quit(const char *fmt, ...)
{
	va_list		ap;

	va_start(ap, fmt);
	err_doit(0, 0, fmt, ap);
	va_end(ap);
	exit(1);
}

/*
 * Print a message and return to caller.
 * Caller specifies "errnoflag".
 */
static void
err_doit(int errnoflag, int error, const char *fmt, va_list ap)
{
	char	buf[MAXLINE];

	vsnprintf(buf, MAXLINE, fmt, ap);
	if (errnoflag)
		snprintf(buf+strlen(buf), MAXLINE-strlen(buf), ": %s",
		  strerror(error));
	strcat(buf, "\n");
	fflush(stdout);		/* in case stdout and stderr are the same */
	fputs(buf, stderr);
	fflush(NULL);		/* flushes all stdio output streams */
}

#include <stdio.h>

int printf(const char *format, ...);　　　　　　　　　　　　　　  //格式化到标准输出
int fprintf(FILE *stream, const char *format, ...);　　　　    //格式化到文件
int sprintf(char *str, const char *format, ...);　　　　　　　　//格式化到字符串
int snprintf(char *str, size_t size, const char *format, ...);//规定了格式化字符串的最大长度

#include <stdarg.h>

int vprintf(const char *format, va_list ap);                 
int vfprintf(FILE *stream, const char *format, va_list ap);
int vsprintf(char *str, const char *format, va_list ap);
int vsnprintf(char *str, size_t size, const char *format, va_list ap);

#include <stdarg.h>
     
       void va_start(va_list ap, last);
       type va_arg(va_list ap, type);
       void va_end(va_list ap);
       void va_copy(va_list dest, va_list src);

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

int test(char *fmt, ...);

int main(int argc, const char *argv[])
{
    test("test", "hello", "world","");
    return 0;
}

int test(char *fmt, ...){
    va_list ap;
    char *temp;

    va_start(ap, fmt);
    while(1){
        temp = va_arg(ap, char *);
        if(temp != ""){
            printf("%s ", temp);
        }
        else
            break;
    }

    va_end(ap);
    return 0;
}

#define va_start(ap, v) (ap = (va_list)&v + _INTSIZEOF(v) )

#define va_arg(ap,t) (*(t *)( (ap += _INTSIZEOF(t)) - _INTSIZEOF(t) )

#define va_end(ap) (ap = (va_list)0)