/* Concatenate variable number of strings.
   Copyright (C) 1991 Free Software Foundation, Inc.
   Written by Fred Fish @ Cygnus Support

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */


/*

NAME

	concat -- concatenate a variable number of strings

SYNOPSIS

	#include <varargs.h>

	char *concat (s1, s2, s3, ..., NULL)

DESCRIPTION

	Concatenate a variable number of strings and return the result
	in freshly malloc'd memory.

	Returns NULL if insufficient memory is available.  The argument
	list is terminated by the first NULL pointer encountered.  Pointers
	to empty strings are ignored.

NOTES

	This function uses xmalloc() which is expected to be a front end
	function to malloc() that deals with low memory situations.  In
	typical use, if malloc() returns NULL then xmalloc() diverts to an
	error handler routine which never returns, and thus xmalloc will
	never return a NULL pointer.  If the client application wishes to
	deal with low memory situations itself, it should supply an xmalloc
	that just directly invokes malloc and blindly returns whatever
	malloc returns.
*/


#include <varargs.h>

#define NULLP (char *)0

extern char *xmalloc ();

/* VARARGS */
char *
concat (va_alist)
     va_dcl
{
  register int length = 0;
  register char *newstr;
  register char *end;
  register char *arg;
  va_list args;

  /* First compute the size of the result and get sufficient memory. */

  va_start (args);
  while ((arg = va_arg (args, char *)) != NULLP)
    {
      length += strlen (arg);
    }
  newstr = (char *) xmalloc (length + 1);
  va_end (args);

  /* Now copy the individual pieces to the result string. */

  if (newstr != NULLP)
    {
      va_start (args);
      end = newstr;
      while ((arg = va_arg (args, char *)) != NULLP)
	{
	  while (*arg)
	    {
	      *end++ = *arg++;
	    }
	}
      *end = '\000';
      va_end (args);
    }

  return (newstr);
}

#ifdef MAIN

/* Simple little test driver. */

main ()
{
  printf ("\"\" = \"%s\"\n", concat (NULLP));
  printf ("\"a\" = \"%s\"\n", concat ("a", NULLP));
  printf ("\"ab\" = \"%s\"\n", concat ("a", "b", NULLP));
  printf ("\"abc\" = \"%s\"\n", concat ("a", "b", "c", NULLP));
  printf ("\"abcd\" = \"%s\"\n", concat ("ab", "cd", NULLP));
  printf ("\"abcde\" = \"%s\"\n", concat ("ab", "c", "de", NULLP));
  printf ("\"abcdef\" = \"%s\"\n", concat ("", "a", "", "bcd", "ef", NULLP));
}

#endif
