C++ Tutorial/template/Template specialization

Partial specialization as end criteria

<source lang="cpp">/* 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.
*/

1. 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";

}</source>

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

Primary template to compute 3 to the Nth and full specialization to end the recursion

<source lang="cpp">/* 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.
*/

1. include <iostream>

// primary template to compute 3 to the Nth template<int N> class Pow3 {

 public:
   enum { result = 3 * Pow3<N-1>::result };

}; // full specialization to end the recursion template<> class Pow3<0> {

 public:
   enum { result = 1 };

}; int main() {

   std::cout << "Pow3<7>::result = " << Pow3<7>::result
             << "\n";

}</source>

Pow3<7>::result = 2187

Template specialization

<source lang="cpp">#include <iostream.h> template <class T> class MyClass {

   T value1, value2;
 public:
   MyClass (T first, T second)
     {value1=first; value2=second;}
   T module () {return 0;}

}; template <> class MyClass <int> {

   int value1, value2;
 public:
   MyClass (int first, int second){
       value1 = first; 
       value2 = second;
   }
   int module (){
       return value1value2;
   }

}; int main () {

 MyClass <int> myints (100,75);
 MyClass <float> myfloats (100.0,75.0);
 cout << myints.module() << "\n";
 cout << myfloats.module() << "\n";
 return 0;

}</source>

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