General rules of passing/returning reference of array (not pointer) to/from a function?

Question

We can pass reference of an array to a function like:

void f(int (&a)[5]);

int x[5];
f(x);     //okay
int y[6];
f(y);     //error - type of y is not `in         


        

Answer 1

If you want to return a reference to an array from a function, the declaration would look like this:

// an array
int global[10];

// function returning a reference to an array
int (&f())[10] {
   return global;
}

The declaration of a function returning a reference to an array looks the same as the declaration of a variable that is a reference to an array - only that the function name is followed by (), which may contain parameter declarations:

int (&variable)[1][2];
int (&functionA())[1][2];
int (&functionB(int param))[1][2];

Such declarations can be made much clearer by using a typedef:

typedef int array_t[10];

array_t& f() {
   return global;
}

If you want it to get really confusing, you can declare a function that takes a reference to an array and also returns such a reference:

template
int (&f(int (¶m)[M][N]))[M][N] {
   return param;
}

Pointers to arrays work the same, only that they use * instead of &.