int const* const x; // C

int const& x; // C++

A reference is functionally equivalent to a const pointer. (Reference reassignment is disallowed. Likewise, you cannot reassign a const pointer. A const pointer is meant to keep its pointee [address].) The difference between them is that C++ const references also allow non-lvalue arguments (temporaries).

It is much easier to read from right to left when decoding types. Look for yourself:

- double (* const convert_to_deg)(double const x) // const pointer to function taking a const double and returning double

- int const (* ptr_to_arr)[42]; // pointer to array of 42 const ints

- int const * arr_of_ptrs[42]; // array of 42 pointers to const ints

- int fun_returning_array_of_ints()[42];

Try it out yourself: https://cdecl.org/

Hence, I am an "East conster". (Many people are "West consters" though.)

You can return function pointers:

typedef struct player_t player_t; // let it be opaque ;)

int game_strategy1(player_t const * const p)

{

    /* Eliminate player */

    return 666;

}

int game_strategy2(player_t const * const p)

{

    /* Follow player */
    
    return 007;

}

int (* const game_strategy(int const strategy_to_use))(player_t const * const p)

{

    if (strategy_to_use == 0)
        return &game_strategy1;

    return &game_strategy2;

}

Functional programming = immutable (const) values + pure functions (no side effects).

Consting for me is also a form of documentation/specification.

"East const" for life! :)

user:	danielozcpp
created:	August 22, 2021
karma:	53