NAME

vprintf, vfprintf, vsprintf − print formatted output of a varargs argument list

SYNOPSIS

#include <stdio.h>
#include <varargs.h>

int vprintf (format, ap)
char ∗format;
va_list ap;

int vfprintf (stream, format, ap)
FILE ∗stream;
char ∗format;
va_list ap;

int vsprintf (s, format, ap)
char ∗s, ∗format;
va_list ap;

DESCRIPTION

Vprintf, vfprintf, and vsprintf are the same as printf, fprintf, and sprintf respectively, except that instead of being called with a variable number of arguments, they are called with an argument list as defined by varargs(5).

EXAMPLE

The following demonstrates how vfprintf could be used to write an error routine:

#include <stdio.h>
#include <varargs.h>
.
.
.
/∗
 ∗error should be called like
 ∗error(function_name, format, arg1, arg2...);
 ∗/
/∗VARARGS0∗/
void
error(va_alist)
/∗ Note that the function_name and format arguments cannot be
 ∗      separately declared because of the definition of varargs.
 ∗/
va_dcl
{
va_list args;
char ∗fmt;
 va_start(args);
 /∗ print out name of function causing error ∗/
(void)fprintf(stderr, "ERROR in %s: ", va_arg(args, char ∗));
fmt = va_arg(args, char ∗);
 /∗ print out remainder of message ∗/
(void)vfprintf(stderr, fmt, args);
va_end(args);
(void)abort( );
}

SEE ALSO

nl_init(3C), printf(3S), varargs(5). 

Hewlett-Packard Company  —  May 11, 2021