vprintf.3s (2010 09)

v
vprintf(3S) vprintf(3S)
NAME
vprintf(), vfprintf(), vsprintf(), vsnprintf() - print formatted output of a varargs argument list
SYNOPSIS
#include <stdarg.h>
#include <stdio.h>
int vprintf(const char *__restrict format, va_list ap);
int vfprintf(FILE *__restrict stream, const char *__restrict format,
va_list ap);
int vsprintf(char *__restrict s, const char *__restrict format,
va_list ap);
int vsnprintf(char *__restrict s, size_t maxsize,
const char *__restrict format, va_list ap);
DESCRIPTION
vprintf(), vfprintf(), vsprintf(), and
vsnprintf() are the same as printf(),
fprintf(), sprintf(), and snprintf() respectively, except that instead of being called with a
variable number of arguments, they are called with an argument list as defined by
<stdarg.h>.
RETURN VALUE
Each function returns the number of bytes transmitted (excluding the
\0 null byte character in the case
of vsprintf()) or a negative value if an output error was encountered.
By default,
vsnprintf() returns a negative value if maxsize is smaller than the number of characters
formatted. In the UNIX 2003 standards environment (see standards (5)) it returns the number of bytes
that would have been written to buffer s , excluding the terminating null byte, if maxsize had been
sufficiently large.
EXAMPLES
The following demonstrates how
vfprintf() could be used to write an error routine:
#include <stdarg.h>
#include <stdio.h>
.
.
.
/*
* error should be called using the form:
* error(function_name, format, arg1, arg2...);
*/
/*VARARGS0*/
void
error(va_alist)
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( );
}
HP-UX 11i Version 3: September 2010 − 1 − Hewlett-Packard Company 1