Partial specialization as end criteria : Template specialization « template « C++ Tutorial

1. C++ Tutorial
2. template
3. Template specialization

/* The following code example is taken from the book
 * "C++ Templates - The Complete Guide"
 * by David Vandevoorde and Nicolai M. Josuttis, Addison-Wesley, 2002
 *
 * (C) Copyright David Vandevoorde and Nicolai M. Josuttis 2002.
 * 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 <iostream>


// primary template
template <int DIM, typename T>
class DotProduct {
  public:
    static T result (T* a, T* b) {
        return *a * *b  +  DotProduct<DIM-1,T>::result(a+1,b+1);
    }
};

// partial specialization as end criteria
template <typename T>
class DotProduct<1,T> {
  public:
    static T result (T* a, T* b) {
        return *a * *b;
    }
};

// convenience function
template <int DIM, typename T>
inline T dot_product (T* a, T* b)
{
    return DotProduct<DIM,T>::result(a,b);
}

int main()
{
    int a[3] = { 1, 2, 3};
    int b[3] = { 5, 6, 7};

              << '\n';
              << '\n';
}

dot_product<3>(a,b) = 38
dot_product<3>(a,a) = 14