C++ Promblem

[ProgrammingFreak]

I am having trouble understadning this programming concept

Example:
typedef struct{
int Helath;
int Armor;
}b_stuff;

Yes that is an example of it, I understand how to do that, but how do you give the variables vaules after they have declared in there, I tried it out of there and I got an error, I tried it in the array and got an error, any help

[RoadMaster]

Edit: Removed because others have answered your question better, and I clearly need to re-read some of my own C++ books as I've forgotten the differences between C and C++, dur...

[svero]

There's two concepts here.. the typedef and the struct

The typedef is just a way of assigning a new name to some type when it's more convenient or if you're having trouble withe the pre-processor (#define's don't work sometimes with pointer types)

So instead of... Sprite* you could write...

typedef Sprite* PSprite;

and then define a function that takes a PSprite (pointer to sprite)

--

Now the struct is something else.. That's a way of grouping things together that belong together. Here's a useful example...



struct PLAYER
{
int Lives;
int Level;
int points;
};


theres a basic struct that has all the information about a player in a basic arcade game. What level they're on, how many lives they have left, and how many points they've accumulated. Then somewhere else in the code you might do...



PLAYER player1;
PLAYER player2;


to create 2 actual players. Or alternately...



PLAYER Players[2];


and then in the game where the player gets some points...



Players[CurrPlayer].points +=250;


etc...

A small note is that a struct is equivalent to a class in C++ where everything is public by default.. so these are the same..



struct A
{
int x;
int y;
};

class A
{
public :
int x;
int y;
};

[ggambett]

You can also init static struct data this way

static b_stuff lStuffs[] = { { 1, 2, 3 }, { 4, 5, 6 } };

This creates an array of two b_stuff structs, the first with 1 life, level 2 and 3 points, and the other with values 4, 5 and 6.

Or create a constructor (the only difference between structs and classes in C++ is that classes are private by default and structs are public).

b_stuff::b_stuff (int nLives, int nLevel, int nPoints) : nLives(nLives), nLevel(nLevel), nPoints(nPoints) {}

You can use it this way

b_stuff pStuff1(1, 2, 3);

or

b_stuff* pStuff2 = new b_sStuff(1, 2, 3);

[mahlzeit]

Small note: There is a difference between C and C++ here. In C, you do need the typedef but in C++ you don't. (Although they may have lifted that restriction in a recent revision of the language specs: the last time I used pure .c files was ages ago.) Anyway, if you look at old sources that may be confusing a little.

[ProgrammingFreak]

Ok I get it kinda

[dmikesell]

You may either want to start with a simpler language (Python, Ruby, etc.) or consider a simpler application than a game with which to learn C++.