====== extdef.h ======
<code>
/**
 * extdef.h - A header of macros to augment the C standard headers.
 *
 * v1.0 - 10/06/2012 - Initial release
 * 
 * Copyright (C) 2012 - Joel Holdsworth
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 **/

#ifndef _EXTDEF_H
#define _EXTDEF_H

#define countof(x) (sizeof(x)/sizeof(x[0]))

#define begin_element(x) (&x[0])
#define end_element(x) (&x[countof(x)])

#endif /* _EXTDEF_H */
</code>

===== Overview =====
extdef.h is a companion header to add extra macros to augment the C/C++ standard set. The header is released under the BSD license.
===== Reference =====
==== countof() ====
This macro is a a companion to the ''sizeof()'' keyword and the [[http://cplusplus.com/reference/clibrary/cstddef/offsetof/|offsetof()]] macro in stddef.h. ''countof'' returns the number of elements in a C style array. The value returned is an unsigned integral value of type ''size_t'' with the amount of bytes between the specified member and the beginning of its structure.
==== begin_element() & end_element() ====
''begin_element()'' returns a pointer to the first element of an array. ''end_element()'' returns a pointer to the first address after the end of the array.

These two macros are provided so that C style array can neatly integrate with [[http://cplusplus.com/reference/algorithm/|STL algorithms]]. This is possible because STL iterators have the same semantic properties. These provide an elegant way to easily search and transform sequence data types.

=== Example ===
Finding the maximum value in an array.
<code>
const int a[] = {1, 3, 2, 5, 4};
const int max = max_element(begin_element(a), end_element(a));
</code>