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

FILE *LogFile;

/* a general error routine */

void errmsg( char *format, ... )
  {
    va_list arglist;

    fprintf( stderr, "Error: " );
    va_start( arglist, format );
    vfprintf( stderr, format, arglist );
    va_end( arglist );
    if( LogFile != NULL ) {
      fprintf( LogFile, "Error: " );
      va_start( arglist, format );
      vfprintf( LogFile, format, arglist );
      va_end( arglist );
    }
  }

void main()
  {
    LogFile = fopen( "error.log", "w" );
    errmsg( "%s %d %s", "Failed", 100, "times" );
  }