template_specialization.cpp

/********************************************/
/************* HOW TO USE TYPES *************/
/********************************************/
#include <iostream>
using namespace std;

/* This can be used indifferently for any type */
template<typename T>
void print_data(T output){
    cout << output << endl;    
}

/* TEMPLATE SPECIALIZATION: it behaves differently for int type */
template<>
void print_data(int output){
    cout << output << ".000" << endl;
}

/* Should you use two types, you need this */
template<typename U, typename S>
void print_double_data(U first, S second){
    cout << first << " " << second << endl;
}

int main() {
    double d = 5.5;
    string s("Hello World");
    int i = 10;
    print_data(d); // it functions with a double...
    print_data(s); // ...and it functions with a string, also
    print_data<int>(i); // let's invoke template specialization!
    print_double_data(d,s); // you need two different types U and S: using a single typename would result in an error
    print_double_data(s,s); // of course, it functions even if U and S are same type
	return 0;
}

In case of regular class templates, the way the class handles different data types is the same; the same code runs for all data types.
Template specialization allows for the definition of a different implementation of a template when a specific type is passed as a template argument.

Template specialization in classes:

template <class T>
class MyClass {
 public:
  MyClass (T x) {
   cout <<x<<" -  not a char"<<endl;
  }
};

template < >
class MyClass<char> {
 public:
  MyClass (char x) {
   cout <<x<<" is a char!"<<endl;
  }
};