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c/c++ structs and pointers question

Started by voidless Mar 7, 2009 at 6:54 AM 7 replies 1.4k views

Original Post

Mar 7, 2009 at 6:54 AM

if i have the following struct: struct x{ int a; int b; }; and in the main() we have: struct x* k; i know i can access a member of k via (*k).a or k->a but i always wondered if both works the same way, or one is different from the other? and if why, and which one is more optimal? thank you

ToohrVyk

238

ToohrVyk

Mar 7, 2009 at 6:57 AM

They're equivalent.

stonemetal

Mar 7, 2009 at 7:33 AM

-> is what is known as syntactic sugar. Something that makes your code look nice but adds no value or power to the language.

DevFred

136

DevFred

Mar 7, 2009 at 7:59 AM

Quote:
Original post by voidless
struct x* k;

In C, the struct keyword is required here, but you don't need it in C++. Just write
x* k;

Of course, there is no such language as C/C++, but I assume you mean C++ when you say C/C++.

Black Knight

116

Black Knight

Mar 7, 2009 at 8:44 AM

Also in C++ struct behaves exactly like a class, the only difference is the members of a struct are public whereas class members default to private.Well thats what I know anyways [smile]

struct Foo
{
int x;
int y;
};

x and y are public.

class Bar
{
int x;
int y;
};

x and y are private.

Am I correct ?

Aardvajk

1,172

Aardvajk

Mar 7, 2009 at 8:49 AM

Quote:
Original post by Black Knight
Am I correct ?

Yes.

Also, inheritance is public by default for structs and private by default for classes.

ToohrVyk

238

ToohrVyk

Mar 7, 2009 at 8:50 AM

Black Knight:

Quote:
The Most Holy C++ Standard, psalm 9.4 (Blessed Be Its Subsections)
A structure is a class defined with the class-key struct; its members and base classes (clause class.derived) are public by default (clause class.access). A union is a class defined with the class-key union; its members are public by default and it holds only one data member at a time (class.union).

voidless

Author

voidless

Mar 7, 2009 at 9:07 AM

thanks for the replies

hamo26

Mar 7, 2009 at 11:40 AM

Historically, A struct is actually the pioneer for it was developed before classes. As some people said a struct is usefull for simple objects if you want to avoid that complicated class decleration (lol).

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