// filename:c2011-7-21-6-8-ex.c
// original examples and/or notes:
// 		(c) ISO/IEC JTC1 SC22 WG14 N1570, April 12, 2011
// 			C2011 7.21.6.8 The vfprintf function
// compile and output mechanism:
// 		(c) Ogawa Kiyoshi, kaizen@gifu-u.ac.jp, December.29, 2013
// compile errors and/or wornings:
// 		(c) Apple LLVM version 4.2 (clang-425.0.27) (based on LLVM 3.2svn)
// 			Target: x86_64-apple-darwin11.4.2 //Thread model: posix
// 		(c) LLVM 2003-2009 University of Illinois at Urbana-Champaign.
// Example
#include <stdarg.h>
#include <stdio.h>
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);
}

int main(void)
{
	error("main", "%s","help me\n");
return printf("7.21.6.8 The vfprintf function \n");
}
// output may be 
//ERROR in main: help me
//7.21.6.8 The vfprintf function