setenv.h

libiconv是一个很不错的字符集转换库。程序接口也很简单

/* Setting environment variables.
   Copyright (C) 2001-2002 Free Software Foundation, Inc.

   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, 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */

#if HAVE_SETENV || HAVE_UNSETENV

/* Get setenv(), unsetenv() declarations.  */
#include <stdlib.h>

#endif

#ifdef	__cplusplus
extern "C" {
#endif

#if !HAVE_SETENV

/* Set NAME to VALUE in the environment.
   If REPLACE is nonzero, overwrite an existing value.  */
extern int setenv (const char *name, const char *value, int replace);

#endif

#if !HAVE_UNSETENV

/* Remove the variable NAME from the environment.  */
extern int unsetenv (const char *name);

#endif

#ifdef	__cplusplus
}
#endif