分配操作符 - 自我分配 [英] Assignment operator - Self-assignment

问题描述

编译器是否对自我分配产生了赋值操作符？

Does the compiler generated assignment operator guard against self assignment?

class T {

   int x;
public:
   T(int X = 0): x(X) {}
};

int main()
{
   T a(1);
   a = a;
}

我总是需要防止自我分配，即使类成员指针类型？

Do I always need to protect against self-assignment even when the class members aren't of pointer type?

推荐答案

编译器是否生成了对自我赋值的赋值操作符？ / p>

Does the compiler generated assignment operator guard against self assignment?

否，它不会。它只执行一个成员方式的副本，其中每个成员都由其自己的赋值运算符（也可以是程序员声明的或编译器生成的）复制。

No, it does not. It merely performs a member-wise copy, where each member is copied by its own assignment operator (which may also be programmer-declared or compiler-generated).

我总是需要防止自我分配，即使类成员不是指针类型吗？

Do I always need to protect against self-assignment even when the class members aren't of pointer type?

不，如果您课程的所有属性（因此他们的属性）都是 POD类型。

No, you do not if all of your class's attributes (and therefore theirs) are POD-types.

当你编写自己的赋值运算符时，如果你想保证你的类的未来，你可以检查自我赋值，即使它们不包含任何指针， 等 。另请考虑复制和交换惯用语。

When writing your own assignment operators you may wish to check for self-assignment if you want to future-proof your class, even if they don't contain any pointers, et cetera. Also consider the copy-and-swap idiom.

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