Re: C++11 - Parameter pack question

[Sidney Marshall <sidneym at frontiernet dot net>]

At 09:12 AM 8/16/2014 +0200, Marc Glisse wrote:
> On Fri, 15 Aug 2014, Sidney Marshall wrote:
>
> > The following code compiles and runs correctly but gives a warning:
> >
> > ----------------------------------------
> > #include<iostream>
> >
> > using namespace std;
> >
> > template<class T>
> > T sum(T value) {
> >  return value;
> > }
> >
> > template<class T, class ... U>
> > auto sum(T value, U ... values) {
> >    return value + sum(values ...);
> > }
> >
> > int main() {
> >  cout << sum(1, 2, 4.6) << endl;
> >  cout << sum(1, "abcde", 2) << endl;
> > }
> > --------------------------------------
> >
> > $ g++ -std=c++11 pack.cpp
> > pack.cpp:11:31: warning: â??sumâ?? function 
> > uses â??autoâ?? type specifier without trailing 
> > return type [enabled by default]
> > auto sum(T value, U ... values) {
>
> The warning should probably specify that this is 
> a C++14 feature. You should be compiling with -std=c++1y.

You are correct - I didn't read section 7.1.6.4 
paragraphs 2 and 5 of the standard correctly. Thank you.

I guess I can't write this function in C++11 this way.


> --
> Marc Glisse

--Sidney Marshall