How to initialize an array in a template class with a custom value?

Question

For example

template<size_t N>
class A
{
    array<int, N> m;
    static A const UNIT {1, 1, ...}; // repeated N times, 
                                     // but I can't because of currently unspecified N
}

How to initialize a template sized array with the custom value 1?

Not sure, but if I see ... in conjunction with templates, I start thinking of using variadic template parameter lists and unpacking. Don't know how to generate these though, using a non type template parameter giving their number. — πάντα ῥεῖ
– πάντα ῥεῖ, Commented Jun 9, 2016 at 23:23
fill does some work. But I don't know how to put it. may be with lambda??? — user1899020
– user1899020, Commented Jun 9, 2016 at 23:26
Ah, well. Yes sure that does it. I was premising you were looking for a compile time solution. — πάντα ῥεῖ
– πάντα ῥεῖ, Commented Jun 9, 2016 at 23:36

Nick Matteo · Accepted Answer · 2016-06-09 23:52:57Z

2

You can use the fill function. This works fine with a static const member, too.

template<size_t N>
class A {
    array<int, N> m;
    public:
    static A const unit;
    A() { m.fill(1); }
};

template<size_t N>
A<N> const A<N>::unit{};

edited Jun 9, 2016 at 23:52

answered Jun 9, 2016 at 23:29

Nick Matteo

4,7401 gold badge26 silver badges38 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

How to initialize an array in a template class with a custom value?

1 Answer 1

Comments

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Related