错误:对非const的引用的初始值必须是一个值 [英] Error: initial value of reference to non-const must be an value

问题描述

class A
{

public:

    int v;
    A * p;
    A& operator*(const A& a)
    {
        return this->v*a.v// here is a red line under this say error initial value of reference to non-const must be an value
    }
    ~A()
    {
        this;
    }
};

int main()
{
    A a;
    a.p = new A;
    delete a.p;
    return 0;

    system("pause");
    return 0;
}

重载*运算符我不能使用它来表示对象本身.为什么会这样.

overloading * operator I cannot use this to represent the object itself. Why this happened.

推荐答案

当然，它说它必须是 lvalue .您正在尝试返回对临时目录的引用.这是不好的业力.

Surely it says that it must be an lvalue. You're trying to return a reference to a temporary. This is bad karma.

此外，它根本不是您想要的.乘法运算符绝对应该返回一个值，而不是引用.

Besides, it's not at all what you want. The multiplication operator should definitely return a value, not a reference.

不确定您的构造函数是什么样子，但假设它采用整数:

Not sure what your constructor looks like, but assuming it takes an integer:

A operator * (A const& other) const
{
    return A{ v * other.v};
};

实际上，您应该更进一步:

And actually you should go a step further:

struct A
{
    A& operator *= (A const& other) { v *= other.v; return *this; }
    A(int i) : v(i) {}
private:
    int v;
}

A operator * (A lh, A const& rh)
{
   A res{std::move(lh)};
   res *= rh;
   return res;
}

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