Return array in C++

Question

I am a total C++ noob, and I am having some trouble returning an array from my methods. I have a header file with the following method declaration:

virtual d         


        

Answer 1

There is a technique for passing arrays that do not decay to pointers. You pass the array by reference, using the syntax below. The required "extra" parens are a syntactical wart, and probably why this usage is not more common. One gets used to it real fast, given the advantages.

void sub(double (&foo)[4])
{
    cout << sizeof(foo) << endl;
}

Prints 32, not sizeof(double*), because the type of foo really is a reference to an array of 4 doubles. Using templates, you can generalize to work for any size of array:

template  sub(double (&foo)[N])
 {
    cout << sizeof(foo) << endl;
 }

 double bar[5];
 double zot[3];
 sub(bar); // ==> 40
 sub(zot); // ==> 24

You can generalize again to handle an any-size array of anything:

template void sub(T(&foo)[N])
    {
        cout << sizeof(foo) << endl;
    }

double bar[5];
char zot[3];
sub(bar); // ==> 40
sub(zot); // ==> 3

and you now have something that captures the abstract idea of "sub" regardless of the type or size of the array you pass it.