Variadic Templates example

Question

Consider following code, I don\'t understand why empty function of print must be defined.

#include 
using namespace std;

void print()
{   
}   
         


        

Answer 1

Recursion is the most general way to program variadic templates, but it's far from the only way. For simple use cases like this, doing a pack expansion directly within a braced initializer list is shorter and likely faster to compile.

template 
void print (const Types&... args)
{   
    using expander = int[];
    (void) expander { 0, (void(cout << args << endl), 0) ...};
}

In C++17, we'll be able to use a fold expression:

template 
void print (const Types&... args)
{   
    (void(cout << args << endl) , ...);
}