Pointers to structures

[omni]

This question seems a little newb compared to the other ones on this forum, but anyway ...

struct exmstruct{
int x;
int y;
int z;
}
...

exmstruct jeff;
exmstruct *expointer;
expointer = &jeff;

Ok so where will "expointer" be pointing to? Will it be the jeff.x? And if I do "expointer += 1" will the pointer be pointing to jeff.y after?

EDIT: Not sure if i'm thinking of structure pointers the right way. I am thinking of structure pointers like array and string pointers. Is this right?

[wtd]

They're entirely the same. A pointer is a pointer is a pointer. It's simply a variable which holds the address in memory of something else.

c++:

struct example_struct {    int x, y, z; }; int main() {    // foo is just an example_struct object    example_struct foo;    // bar is a pointer to an example_struct object    example_struct * bar;    // &foo gets the memory address for foo    // the rest assigns that memory address to the bar pointer    bar = &foo;    // the above could have been better written:    // example_struct * bar = &foo;    return 0; }

Now, theoretically bar points to the first member of example_struct, or x. However, there is no guarantee in C++ that members will be laid out in a given fashion, and memory may be padded in such a way that doing pointer arithmetic of this sort is evil.

The simple answer is: don't do it. Use foo.x, foo.y, foo.z.

[Andy]

c++:

struct exmstruct {    int x, y, z; }; int main() {     exmstruct jeff;     exmstruct *expointer;     expointer = &jeff;     expointer ->x=0;     expointer ->y=0;     expointer ->z=0; }

u use -> to access the sub variables

[wtd]

Andy wrote:

c++:

struct exmstruct {    int x, y, z; }; int main() {     exmstruct jeff;     exmstruct *expointer;     expointer = &jeff;     expointer ->x=0;     expointer ->y=0;     expointer ->z=0; }

u use -> to access the sub variables

"members"

Structs in C++ are simply classes where everything's public by default.

[Andy]

o oops.. it doesnt work on structs? hmmmm heh use classes

[md]

no no, -> works on structs in C++, but structs are really just classes where everything is public

[Mazer]

By default. You can still make members protected/private, right?

[wtd]

Coutsos wrote:

By default. You can still make members protected/private, right?

Absolutely.

You can subclass structs, too.

[omni]

If I want to create an array of strings, would I just make a 2d array?

[Andy]

didnt u learn the string class??? u guys didnt do classes???

[omni]

I'm self teaching myself this. So there is no "guys" And no I didn't learn string classes or classes in general : /

[Andy]

windsor eh? do u go to massey? anyways, you should read up on classes, they are very very useful

[Mazer]

omni: yes, a 2D char array will give you an array of strings. That said, character arrays can really be a pain. You should look up the std string class when you get a chance.
Also, find "Thinking in C++" if you can. It's floating around the internet for free and supposedly a good read. (I should read it myself when I have some time).

[omni]

@ Andy : yea i go to massey gr.11
@coustos: K i'll look it up

BTw is there any command to clear the screen? using std::cout all the time just makes the screen scroll down and that doesnt really look nice.

[Mazer]

As far as I know, yes, but they aren't very good. Ultimately you must ask, do you really need to clear the console screen?