Define class with iterator support and direct element access : define iterator operator « template « C++ Tutorial

1. C++ Tutorial
2. template
3. define iterator operator

/* The following code example is taken from the book
 * "The C++ Standard Library - A Tutorial and Reference"
 * by Nicolai M. Josuttis, Addison-Wesley, 1999
 *
 * (C) Copyright Nicolai M. Josuttis 1999.
 * Permission to copy, use, modify, sell and distribute this software
 * is granted provided this copyright notice appears in all copies.
 * This software is provided "as is" without express or implied
 * warranty, and with no claim as to its suitability for any purpose.
 */
#include <algorithm>
#include <functional>
#include <iostream>
#include <cstddef>
using namespace std;



/* PRINT_ELEMENTS()
 * - prints optional C-string optcstr followed by
 * - all elements of the collection coll
 * - separated by spaces
 */
template <class T>
inline void PRINT_ELEMENTS (const T& coll, const char* optcstr="")
{
    typename T::const_iterator pos;

    std::cout << optcstr;
    for (pos=coll.begin(); pos!=coll.end(); ++pos) {
        std::cout << *pos << ' ';
    }
    std::cout << std::endl;
}


template<class T, std::size_t thesize>
class carray {
  private:
    T v[thesize];    // fixed-size array of elements of type T

  public:
    // type definitions
    typedef T        value_type;
    typedef T*       iterator;
    typedef const T* const_iterator;
    typedef T&       reference;
    typedef const T& const_reference;
    typedef std::size_t    size_type;
    typedef std::ptrdiff_t difference_type;

    // iterator support
    iterator begin() { return v; }
    const_iterator begin() const { return v; }
    iterator end() { return v+thesize; }
    const_iterator end() const { return v+thesize; }

    // direct element access
    reference operator[](std::size_t i) { return v[i]; }
    const_reference operator[](std::size_t i) const { return v[i]; }

    // size is constant
    size_type size() const { return thesize; }
    size_type max_size() const { return thesize; }

    // conversion to ordinary array
    T* as_array() { return v; }
};

int main()
{
    carray<int,10> a;

    for (unsigned i=0; i<a.size(); ++i) {
        a[i] = i+1;
    }
    PRINT_ELEMENTS(a);

    reverse(a.begin(),a.end());
    PRINT_ELEMENTS(a);

    transform(a.begin(),a.end(),    // source
              a.begin(),            // destination
              negate<int>());       // operation
    PRINT_ELEMENTS(a);
}

1 2 3 4 5 6 7 8 9 10
10 9 8 7 6 5 4 3 2 1
-10 -9 -8 -7 -6 -5 -4 -3 -2 -1