The term member template refers to both member function templates and nested class templates. Member function templates are template functions that are members of a class or class template.

Member functions can be function templates in several contexts. All functions of class templates are generic but are not referred to as member templates or member function templates. If these member functions take their own template arguments, they are considered to be member function templates.

Member function templates of nontemplate or template classes are declared as function templates with their template parameters.

// member_function_templates.cpp  
struct X  
{  
   template <class T> void mf(T* t) {}  
};  
  
int main()  
{  
   int i;  
   X* x = new X();  
   x->mf(&i);  
}  

The following example shows a member function template of a template class.

// member_function_templates2.cpp  
template<typename T>  
class X  
{  
public:  
   template<typename U>  
   void mf(const U &u)  
   {  
   }  
};  
  
int main()  
{  
}  

// defining_member_templates_outside_class.cpp  
template<typename T>  
class X  
{  
public:  
   template<typename U>  
   void mf(const U &u);  
};  
  
template<typename T> template <typename U>  
void X<T>::mf(const U &u)  
{  
}  
  
int main()  
{  
}  

Local classes are not allowed to have member templates.

Member template functions cannot be virtual functions and cannot override virtual functions from a base class when they are declared with the same name as a base class virtual function.

The following example shows a templated user-defined conversion:

// templated_user_defined_conversions.cpp  
template <class T>  
struct S  
{  
   template <class U> operator S<U>()  
   {  
      return S<U>();  
   }  
};  
  
int main()  
{  
   S<int> s1;  
   S<long> s2 = s1;  // Convert s1 using UDC and copy constructs S<long>.  
}  

Function Templates