Really simple question
Author
Ive been learning C++, but along the way Ive come across this
typedef struct store_typ {
int oreos
//more stuff, whatever
} store, *store_ptr
How does this relate to making a structure or class for what Ive probably seen, using class keyword. Is this basically declaring a structure in C, how do the two words relate, store and store_ptr relate to store_typ? Thanks
First off, you need to know that in C, if you declared a struct, you had to type the keyword struct when declaring a variable of that type. For example:
struct store_typ{
int a;
};
struct store_typ s;
By using typedef, you are essentially setting up a shortcut to typing ''struct store_typ''. Instead, you can use just ''store'' (if you do things as typed in your example). Similarly, ''store_ptr'' can be used in place of
struct store_typ* sp;
Instead of the above, you can type
store_ptr sp;
Essentially, you are just saving yourself some typing. Other than that, it really isn''t doing anything.
You aren''t creating a variable of that type, you are just giving the type a new, more convenient to type name. I hope that makes sense and I hope I was clear enough to help you out.
struct store_typ{
int a;
};
struct store_typ s;
By using typedef, you are essentially setting up a shortcut to typing ''struct store_typ''. Instead, you can use just ''store'' (if you do things as typed in your example). Similarly, ''store_ptr'' can be used in place of
struct store_typ* sp;
Instead of the above, you can type
store_ptr sp;
Essentially, you are just saving yourself some typing. Other than that, it really isn''t doing anything.
You aren''t creating a variable of that type, you are just giving the type a new, more convenient to type name. I hope that makes sense and I hope I was clear enough to help you out.
A class and data structure are basically the same thing. The only real difference is that a class comes with constructors destructors (local functions that are called whenever a class of that type are created or destroyed).
when you see
It defines a new type, similar to ''int'' or ''char'' defined as ''store'', and also, if you want to make it a pointer, ''store_ptr''... so that you could make the following declaration:
There you go. The only difference is that in C++ you can go:
... and basically get the same effect (without the pointer).
In C++, however, you can also use classes, which do basically the same thing.
... and get the same effect. The only difference is that all class member data default to private (couldn''t be changed or accessed), while structs are public. Also, classes will call a default constructor and destructor.
Hope that helps!
- Goblin
"In order to understand the full depth of mankind, you must first seperate the word into its component parts: 'mank' and 'ind'."
when you see
typedef struct store_typ{int oreos;} store, *store_ptr; It defines a new type, similar to ''int'' or ''char'' defined as ''store'', and also, if you want to make it a pointer, ''store_ptr''... so that you could make the following declaration:
store safeway;// safeway automatically has the integer member variable called oreossafeway.oreos = 4;store_ptr* albertsons;albertsons->oreos = 3; There you go. The only difference is that in C++ you can go:
struct store{int oreos;};store costco;costco.oreos = 1; ... and basically get the same effect (without the pointer).
In C++, however, you can also use classes, which do basically the same thing.
class store{public:int oreos;};store payless;payless.oreos = 7; ... and get the same effect. The only difference is that all class member data default to private (couldn''t be changed or accessed), while structs are public. Also, classes will call a default constructor and destructor.
Hope that helps!
- Goblin
"In order to understand the full depth of mankind, you must first seperate the word into its component parts: 'mank' and 'ind'."
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