Question

I am looking for a way to identify primitives types in a template class definition.

I mean, having this class :

template<class T> class A{ void doWork(){    if(T isPrimitiveType())      doSomething();    else      doSomethingElse();  } private: T *t;  }; 

Is there is any way to ‘implement’ isPrimitiveType().

Answer 1

UPDATE: Since C++11, use the is_fundamental template from the standard library:

#include <type_traits>  template<class T> void test() {     if (std::is_fundamental<T>::value) {         // ...     } else {         // ...     } } 

---

// Generic: Not primitive template<class T> bool isPrimitiveType() {     return false; }  // Now, you have to create specializations for **all** primitive types  template<> bool isPrimitiveType<int>() {     return true; }  // TODO: bool, double, char, ....  // Usage: template<class T> void test() {     if (isPrimitiveType<T>()) {         std::cout << 'Primitive' << std::endl;     } else {         std::cout << 'Not primitive' << std::endl;     }  } 

In order to save the function call overhead, use structs:

template<class T> struct IsPrimitiveType {     enum { VALUE = 0 }; };  template<> struct IsPrimitiveType<int> {     enum { VALUE = 1 }; };  // ...  template<class T> void test() {     if (IsPrimitiveType<T>::VALUE) {         // ...     } else {         // ...     } } 

As others have pointed out, you can save your time implementing that by yourself and use is_fundamental from the Boost Type Traits Library, which seems to do exactly the same.