Should I use the same name for a member variable and a function parameter in C++?

Question

I am wondering if it is a good practice to use the same name for both a member variable and a function parameter in C++.

I come from a Java backgro

Answer 1

Normally people just put an underscore after the variable or use shorter less descriptive var names for the function parameter.

I personally do not like the same name thing because when reading it, it is easy to make mistakes.

Answer 2

This is more a style issue than anything else. Most of the time, there's no issue: state is a very poor name for a variable or a value, as variables and values should be qualified nouns, e.g.:

void setState( PlayerState* newState )
{
    currentState = newState;
}

In theory, anyway. In practice, I've found it useful to use prefixes, along the lines of:

class Player
{
    PlayerState* myState;
public:
    void setState( PlayerState* newState )
    {
        myState = newState;
    }
};

When reading the code, if the name starts with my, it's clearly a member variable (and if it starts with our, it's a static member variable).

Note too that in the constructor, you can do things like:

Player::Player( PlayerState* state )
    : state( state )
{
}

I'm not sure what this does for readability, however:

Player::Player( PlayerState* initialState )
    : myState( initialState )
{
}

looks a lot clearer (but for simple data holders, the distinction might not be so significant).

Answer 3

Do it this way:

class Player
{
    public:
    void setState(PlayerState *state)
    {
        this->m_state = state;
    }

    private:
       PlayerState *m_state;
}

You'll thank me some time later on. Haha.. (:

The "m_" ("Member") prefix distinguish members from functions and other stuff. Very useful with stuff like intellisense (or any other IDE auto-suggestion).

Also, mark m_state as const if you do not intend to change it later. Just in case.

Answer 4

There is not really any difference between the C++ and Java, the only drawback is that you have to type this->state = state instead of state = arg.

But your code is perfectly acceptable, it's more of styling than anything else.

Answer 5

I would suggest you to follow some coding style convention. Personally I use the:

class Player
{
    public:
    void setState(PlayerState *state)
    {
        _state = state;
    }

    private:
       PlayerState* _state;
}

Answer 6

It's fine, in-fact it might even be good form, so long as it's only ever in your constructor.