C++ arrays as function arguments

Question

• Can I pass arrays to functions just as I would do with primitives such as int and bool?
• Can I pass them by value?
• How does the function know of the size of the array it is passed?

Answer 1

Can I pass arrays to functions just as I would do with primitives such as int and bool?

Yes, but only using pointers (that is: by reference).

Can I pass them by value?

No. You can create classes that support that, but plain arrays don't.

How does the function know of the size of the array it is passed?

It doesn't. That's a reason to use things like vector<T> instead of T *.

Clarification

A function can take a reference or pointer to an array of a specific size:

void func(char (*p)[13])
{
    for (int n = 0; n < 13; ++n)
        printf("%c", (*p)[n]);
}

int main()
{
    char a[13] = "hello, world";
    func(&a);

    char b[5] = "oops";
    // next line won't compile
    // func(&b);

    return 0;
}

I'm pretty sure this is not what the OP was looking for, however.

Answer 2

You can pass arrays the usual way C does it(arrays decay to pointers), or you can pass them by reference but they can't be passed by value. For the second method, they carry their size with them:

template <std::size_t size>
void fun( int (&arr)[size] )
{
   for(std::size_t i = 0; i < size; ++i) /* do something with arr[i] */ ;
}

Most of the time, using std::vector or another sequence in the standard library is just more elegant unless you need native arrays specifically.