C语言 -> 和 . 在结构中？
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Difference between -> and . in a struct?
提问by Sam
If I have a struct like
如果我有一个像
struct account {
int account_number;
};
Then what's the difference between doing
那么这样做有什么区别
myAccount.account_number;
and
和
myAccount->account_number;
or isn't there a difference?
还是没有区别？
If there's no difference, why wouldn't you just use the .notation rather than ->? ->seems so messy.
如果没有区别，为什么不使用.符号而不是->？->看起来好乱
回答by rmk
-> is a shorthand for (*x).field, where xis a pointer to a variable of type struct account, and fieldis a field in the struct, such as account_number.
-> 是 的简写(*x).field，其中x是指向类型变量的指针struct account，field是结构中的字段，例如account_number.
If you have a pointer to a struct, then saying
如果你有一个指向结构的指针，那么说
accountp->account_number;
is much more concise than
比
(*accountp).account_number;
回答by CRM
You use .when you're dealing with variables. You use ->when you are dealing with pointers.
您可以使用.，当你处理变量。您可以使用->，当你正在处理的指针。
For example:
例如：
struct account {
int account_number;
};
Declare a new variable of type struct account:
声明一个新的类型变量struct account：
struct account s;
...
// initializing the variable
s.account_number = 1;
Declare aas a pointer to struct account:
声明a为指向 的指针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;
Usinga->account_number = 1;是另一种语法(*a).account_number = 1;
I hope this helps.
我希望这有帮助。
回答by Rob?
You use the different notation according to whether the left-hand side is a object or a pointer.
根据左侧是对象还是指针使用不同的表示法。
// 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by Grady Player
-> is a pointer dereference and . accessor combined
-> 是一个指针解引用和 . 存取器组合
回答by Juan Pablo Califano
If myAccountis a pointer, use this syntax:
如果myAccount是指针，请使用以下语法：
myAccount->account_number;
If it's not, use this one instead:
如果不是，请改用这个：
myAccount.account_number;
回答by teja
yes you can use struct membrsboth the ways...
是的，您可以同时使用结构成员...
one is with DOt:(" .")
一个是 DOt:(" .")
myAccount.account_number;
anotherone is:(" ->")
另一个是:(" ->")
(&myAccount)->account_number;
回答by speCial
printf("Book title: %s\n", book->subject);
printf("Book code: %d\n", (*book).book_code);
printf("Book title: %s\n", book->subject);
printf("Book code: %d\n", (*book).book_code);
