How to instantiate only part of a function template if a condition is true

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Type traits:

#include <iostream>
#include <type_traits> // C++0x
//#include <tr1/type_traits> // C++03, use std::tr1

template<typename T>
void printType(T param)
{
  if(std::is_same<T,char*>::value)
        std::cout << "char*" << endl;
  else if(std::is_same<T,int>::value)
        std::cout << "int" << endl;
  else
        std::cout << "???" << endl;
}

Or even better yet, just overload the function:

template<class T>
void printType(T partam){
  std::cout << "???" << endl;
}

void printType(char* partam){
  std::cout << "char*" << endl;
}

void printType(int partam){
  std::cout << "int" << endl;
}

Partial ordering will take care that the correct function is called. Also, overloading is preferred to template specialization in the general case, see this and this artice for why. Might not apply for you if you totally have to print the type, as implicit conversions are considered for overloaded functions.

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