VPRINTF(3S)							   VPRINTF(3S)

NAME    [Toc]    [Back]

     vprintf, vfprintf,	vsnprintf, vsprintf - print formatted output of	a
     variable argument list

SYNOPSIS    [Toc]    [Back]

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

     int vprintf (const	char *format, va_list arg);

     int vfprintf (FILE	*stream, const char *format, va_list arg);

     int vsnprintf (char *s, size_t len, const char *format, va_list arg);

     int vsprintf (char	*s, const char *format,	va_list	arg);

DESCRIPTION    [Toc]    [Back]

     vprintf, vfprintf,	vsnprintf, and vsprintf	are the	same as	printf,
     fprintf, snprintf,	and sprintf respectively, except that instead of being
     called with a variable number of arguments, they are called with an
     argument list, arg, as defined by stdarg(5).  The arg parameter must be
     initialized by the	va_start macro (and possibly subsequent	va_arg calls).
     The vprintf, vfprintf, vsnprintf, and vsprintf functions do not invoke
     the va_end	macro.

EXAMPLE    [Toc]    [Back]

     The following demonstrates	the use	of vfprintf to write an	error routine.

     The stdarg.h header file defines the type va_list and a set of macros for
     advancing through a list of arguments whose number	and types may vary.
     The argument ap to	the vprint family of routines is of type va_list.
     This argument is used with	the stdarg.h header file macros	va_start,
     va_arg and	va_end [see va_start, va_arg, and va_end in stdarg(5)].

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

     /*
      *	  error	should be called as:
      *	  error(function_name, format, arg1, arg2 ...);
      */
     void
     error(char	*function_name,	char *format, ...)
     {
	  va_list args;

	  va_start(args, format);
	  /* print out name of function	causing	error */
	  fprintf(stderr, "ERROR in %s:	", function_name);
	  /* print out remainder of message */
	  vfprintf(stderr, format, args);
	  va_end(args);



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VPRINTF(3S)							   VPRINTF(3S)



     }

SEE ALSO    [Toc]    [Back]

     printf(3S), stdarg(5).

DIAGNOSTICS    [Toc]    [Back]

     vprintf, vfprintf,	vsnprintf, and vsprintf	return the number of
     characters	transmitted, or	return -1 if an	error was encountered.


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