使用std :: addressof（）函数模板而不使用operator&在C ++中？ [英] Is there any advantage of using std::addressof() function template instead of using operator& in C++?

问题描述

如果 addressof operator& 运行良好，那么为什么C ++引入了 addressof（）功能？ & 运算符从一开始就是C ++的一部分-那么为什么要引入这个新函数？与C的& 运算符相比，它提供任何优势吗？

If addressof operator& works well then why C++ has introduced addressof() function? The & operator is part of C++ from the beginning - why this new function is introduced then? Does it offer any advantages over C's & operator?

推荐答案

一元 operator& 可能会因类类型的重载而为您提供除对象地址以外的其他内容，而 std :: addressof（）将始终为您提供其实际地址。 ：

The unary operator& might be overloaded for class types to give you something other than the object's address, while std::addressof() will always give you its actual address.
Contrived example:

#include <memory>
#include <iostream>

struct A {
    A* operator &() {return nullptr;}
};

int main () {
    A a;
    std::cout << &a << '\n';              // Prints 0
    std::cout << std::addressof(a);       // Prints a's actual address
}

如果您想知道这样做何时有用：< br>
存在哪些合理的原因使一元代码过载运算符& ;?

If you wonder when doing this is useful:
What legitimate reasons exist to overload the unary operator&?

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