c++ - 内置类型的运算符函数

Question

如何为内置类型定义的运算符显式使用底层运算符函数？看代码:

struct Int
{
    Int() = default;
    Int(int initial)
    {
        i = initial;
    }

    Int operator+(Int other)
    {
        return Int(i + other.i);
    }

    int i;
};

std::ostream& operator<< (std::ostream &out, const Int& data)
{
    out << data.i;
    return out;
}

int main()
{
    Int a, b = 5, c = 5;
    a = b + c;

    std::cout << a << std::endl;

    Int d, e = 5, f = 5;
    d.operator=(e.operator+(f));  // possible with user defined types

    std::cout << d << std::endl;

    int g, h = 5, j = 5;
    g.operator=(h.operator+(j));  // illegal

    return 0;
}

标有“非法”的部分产生以下错误:

request for member 'operator+' in 'h', which is of non-class type 'int'

我知道你不能在非类类型的 int 上调用方法。问题是 operator+ 的含义在哪里定义以及是否可以显式使用它。

Answer 1

How can I explicitly use the underlying operator functions for operators defined for built-in types?

你不能。

如果您正在寻找标准的相关部分，那么它应该是:

16.5 Overloaded operators

6 An operator function shall either be a non-static member function or be a non-member function that has at least one parameter whose type is a class, a reference to a class, an enumeration, or a reference to an enumeration.