Question

I have following class:

template <size_t size>
class Araye{
 public:
  Araye(int input[]){
   for (int i=0;i<size;i++)
    araye[i]=input[i];
  }
  int araye[size];
};

How should I write a cast-to-reference-to-array operator for this class so that following works:

int adad[3]={1,2,3};
Araye<3> araye(adad);
int (&reference)[3]=araye;

Answer 1

template <size_t size> class Araye {
public:
    typedef int (&array_ref)[size];    
    operator array_ref () { return araye; }
    // ...

Or with identity (thanks Johannes):

operator typename identity<int[size]>::type &() { return araye; }

With that your example works, but i’d prefer the following declaration instead:

Araye<3>::array_ref reference = araye;  

There usually should be no need for this though as the subscripting operator should cover most needs:

int& operator[](size_t i) { return araye[i]; }

Note that if you are ok with limiting your class to being an aggregate, you could shorten your sample to the following instead:

template <size_t size> struct Araye {
    int araye[size];
    typedef int (&array_ref)[size];    
    operator array_ref () { return araye; }
};

Araye<3> araye = {1,2,3};
Araye<3>::array_ref reference = araye;