extdef.h

/**
 * 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 */

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 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 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.

const int a[] = {1, 3, 2, 5, 4};
const int max = max_element(begin_element(a), end_element(a));