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;
}
overloading * operator I cannot use this to represent the object itself. Why this happened.
Surely it says that it must be an lvalue. You're trying to return a reference to a temporary. This is bad karma.
Besides, it's not at all what you want. The multiplication operator should definitely return a value, not a reference.
Not sure what your constructor looks like, but assuming it takes an integer:
A operator * (A const& other) const
{
return A{ v * other.v};
};
Edit:
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;
}
this->v*a.v evaluates to an int. An int cannot be converted to an A&.
Use
A operator*(const A& a) // Return a value, not a reference.
{
A res;
res.v = this->v*a.v;
return res;
}
You should make the member function a const member function too since it does not modify the object.
A operator*(const A& a) const
{
A res;
res.v = this->v*a.v;
return res;
}
The result of this->v * a.v is an rvalue, a temporary unnamed value. As a temporary, it cannot bind to a non-const reference. Only lvalues can bind to non-const references. That's what the error "initial value of reference to non-const must be an lvalue" is referring to.
However, you don't want to return a const reference either, you want to return the value by value:
A operator*(const A& a) { … }
^ remove &
Note: this will not fix your code completely as you're trying to return an int where you declared to return an A, and int isn't implicitly convertible to A in your current code.
