Difference between -> and . in a struct?

问题

If I have a struct like

struct account {
   int account_number;
};

Then what's the difference between doing

myAccount.account_number;

and

myAccount->account_number;

or isn't there a difference?

If there's no difference, why wouldn't you just use the . notation rather than ->? -> seems so messy.

回答1:

-> is a shorthand for (*x).field, where x is a pointer to a variable of type struct account, and field is a field in the struct, such as account_number.

If you have a pointer to a struct, then saying

accountp->account_number;

is much more concise than

(*accountp).account_number;

回答2:

You use . when you're dealing with variables. You use -> when you are dealing with pointers.

For example:

struct account {
   int account_number;
};

Declare a new variable of type struct account:

struct account s;
...
// initializing the variable
s.account_number = 1;

Declare a as a pointer to struct account:

struct account *a;
...
// initializing the variable
a = &some_account;  // point the pointer to some_account
a->account_number = 1; // modifying the value of account_number

Using a->account_number = 1; is an alternate syntax for (*a).account_number = 1;

I hope this helps.

回答3:

You use the different notation according to whether the left-hand side is a object or a pointer.

// correct:
struct account myAccount;
myAccount.account_number;

// also correct:
struct account* pMyAccount;
pMyAccount->account_number;

// also, also correct
(*pMyAccount).account_number;

// incorrect:
myAccount->account_number;
pMyAccount.account_number;

回答4:

-> is a pointer dereference and . accessor combined

回答5:

If myAccount is a pointer, use this syntax:

myAccount->account_number;

If it's not, use this one instead:

myAccount.account_number;

回答6:

yes you can use struct membrs both the ways...

one is with DOt:(" . ")

myAccount.account_number;

anotherone is:(" -> ")

(&myAccount)->account_number;

回答7:

printf("Book title: %s\n", book->subject); printf("Book code: %d\n", (*book).book_code);

来源：https://stackoverflow.com/questions/5998599/difference-between-and-in-a-struct

标签

struct