Class or Struct?

**swgh** · 08-27-2006

Hi I am making a pretty large text game and I now have to make the player file.
I am torn betwen either this:

Code:

struct Player
{
    static string m_nm;
    static int m_hp;
};

string m_nm = "";
int m_hp = 100;

which looks like I am attempting to find a way round of not global variables

or this way: ps - this a basic example of what I might do

Code:

class Player
{
public:
    Player();
    ~Player();

protected:
// pointers
    string *m_nm;
    int *m_hp;
};

Player::Player()
{
    m_nm = new string("");
    m_hp = new int(100);
}

Player::~Player()
{
    delete m_nm;
    m_nm = NULL;
    delete m_hp;
    m_hp = NULL;
}

int main()
{
    Player *play = new Player;

    delete play;
    play = NULL;

   return 0;
}

Basicly, I was thinking of doing the second method, all the Player data members
woulds be derived from a base class.

Which method is best to use?

**cboard_member** · 08-27-2006

I would go with the class method every time.
Oh and you might find this macro useful:

Code:

#define SAFE_DELETE( p ) \
{ \
    if ( p ) \
    { \
        delete p; \
        p = NULL; \
    } \
}

Note that I would line up the '\' vertically but it's a pain on this forum.

EDIT: I only use struct's for smaller collections of data, like messages. Of course, use whatever you prefer.

**Salem** · 08-27-2006

How is that any safer than delete p; p = NULL;
deleteing NULL is harmless, and it won't protect you from non-NULL pointers which shouldn't be deleted.

Furthermore, what are you going to do when you should be using delete [ ] p;

**Kurisu33** · 08-27-2006

Class is the way to go because you will have functions inside the Player class to manipulate its data members. Although I would lay off of the pointers and the obsession with dynamic memory allocation where it isn't needed you are inviting unnecessary memory leak issues, etc.

**Mario F.** · 08-27-2006

http://www.parashift.com/c++-faq-lit...s.html#faq-7.8

A struct has its members public by default, whereas a class has them private. If you don't come from a C background this difference may seem unimportant. Especially since you can still move from a struct to a class and viceversa by simply adjusting the access labels. So... who cares? Right?

Well, you do

Think of the difference between both and use that as the basis for your decision. If you want to build an object class that is mainly composed of public access members (functions and data), use a struct. Otherwise use a class. You can still do the other way around, nothing stopping you. The compiler will not care as long as the access labels are correctly placed. But... you and all other humans reading your code will more readily understand it.

**cboard_member** · 08-27-2006

Originally Posted by Salem

How is that any safer than delete p; p = NULL;
deleteing NULL is harmless, and it won't protect you from non-NULL pointers which shouldn't be deleted.

Furthermore, what are you going to do when you should be using delete [ ] p;

It's not "safer", sorry I worded it wrong. Convenient is the word.

I define two macros, SAFE_DELETE and SAFE_DELETE_ARRAY.

**VirtualAce** · 08-27-2006

How is that any safer than delete p; p = NULL;
deleteing NULL is harmless, and it won't protect you from non-NULL pointers which shouldn't be deleted.

Furthermore, what are you going to do when you should be using delete [ ] p;

This is if and only if the compiler you are using follows the standard. MSVC 2005 tends to be much better than MSVC 6, but will often times still fire off an exception when attempting to delete a NULL pointer. Perhaps they left it in there as a pre-cautionary measure to help the programmer find obvious errors.

SAFE_DELETE, SAFE_DELETE_ARRAY and SAFE_RELEASE have been in just about every game programming book I've purchased in one form or another. It would be interesting to see what www.gamasutra.com has to say about the issue.

For now, I'll use them because if anything it is a fore-warning to me that I'm not doing something right in my code.

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