C++ Variadic Function Templates of Known Type

Question

I\'m currently trying to get my head around some of the things I can do with variadic template support. Let\'s say I have a function like this -

template <         


        

Answer 1

If you know the types before, you can use function overload with std:initializer_list :

#include 
#include 

void foo( std::initializer_list l )
{
    for ( auto el : l )
        // do something
}

void foo( std::initializer_list l )
{
}

void foo( std::initializer_list l )
{
}

int main()
{
    foo( {1, 2, 3, 4 } );
    foo( {1.1f, 2.1f, 3.1f, 4.1f } );
    foo( { "foo", "bar", "foo", "foo" } );
    return 0;
}

If you use Visual Studio 2012, you might need the Visual C++ Compiler November 2012 CTP.

EDIT : If you still want to use variadic template, you can do :

template 
void foo( )
{
    int len = sizeof...(Args);
    int vals[] = {Args...};
    // ...
}

// And

foo<1, 2, 3, 4>();

But you have to remember that it is not working with float and std::string for example : you will end with 'float': illegal type for non-type template parameter. float is not legal as a non-type template parameter, this is to do with precision, floating point numbers cannot be precisely represented, and the likelyhood of you referring to the same type can depend on how the number is represented.