如何解決此錯誤，其原因是什么？

Question

我收到一個錯誤，當我單擊查看錯誤時，我將我帶到一個名為xutility的文檔中。

這是兩個錯誤：

1. 錯誤C2064術語的計算結果不等於帶有2個參數的函數。 Studio \\ 2019 \\ Community \\ VC \\ Tools \\ MSVC \\ 14.21.27702 \\ include \\ xutility 624

2.錯誤C2056非法表達式Funtwo C：\\ Program Files（x86）\\ Microsoft Visual Studio \\ 2019 \\ Community \\ VC \\ Tools \\ MSVC \\ 14.21.27702 \\ include \\ xutility 624

然后當我查看第624行時，它向我顯示了這一點

// FUNCTION TEMPLATE _Debug_lt_pred
template <class _Pr, class _Ty1, class _Ty2>
constexpr bool _Debug_lt_pred(_Pr&& _Pred, _Ty1&& _Left, _Ty2&& _Right) _NOEXCEPT_COND(
    noexcept(_Pred(_Left, _Right))
    && noexcept(_Pred(_Right, _Left))) { // test if _Pred(_Left, _Right) and _Pred is strict weak ordering
    const auto _Result = static_cast<bool>(_Pred(_Left, _Right));
    if (_Result) {
        _STL_VERIFY(!_Pred(_Right, _Left), "invalid comparator");
    }

    return _Result;
}

我的課：

class Vector3D : public Vector2
{
public:

    Vector3D();
    ~Vector3D();
    double GetMagnitude();
    void Normalize();
    void scale(Vector3D vector);
    void scale(double vector3x, double vector3y, double vector3z);

    Vector3D operator -();
    Vector3D operator +(Vector3D other);
    Vector3D operator -(Vector3D other);
    Vector3D operator *(Vector3D other);
    Vector3D operator /(Vector3D other);

    bool operator < (Vector3D other);
    bool operator > (Vector3D other);
    bool operator <= (Vector3D other);
    bool operator >= (Vector3D other);
    bool operator == (Vector3D other);
    bool operator != (Vector3D other);

    void operator = (Vector3D other);
    void operator += (Vector3D other);
    void operator -= (Vector3D other);
    void operator *= (Vector3D other);
    void operator /= (Vector3D other);

    friend ostream& operator <<(ostream& out, const Vector3D& v);
    friend istream& operator >>(istream& in, Vector3D& v);

    double m_z = 0;
};

<運營商實施

bool Vector3D::operator<(Vector3D other)
{
    if (GetMagnitude() < other.GetMagnitude())
        return true;
    return false;
}

對於每個成員的實施：

Vector3D::Vector3D()
{
}

Vector3D::~Vector3D()
{
}

double Vector3D::GetMagnitude()
{
    return sqrt(pow(m_x, 2) + pow(m_y, 2) + pow(m_z, 2));
}

void Vector3D::Normalize()
{
    double maxValue = std::max(m_x, m_y, m_z);
    m_x = m_x / maxValue;
    m_y = m_y / maxValue;
    m_z = m_z / maxValue;
}

void Vector3D::scale(Vector3D vector)
{
    m_x *= vector.m_x;
    m_y *= vector.m_y;
    m_z *= vector.m_z;
}

void Vector3D::scale(double vector3x, double vector3y, double vector3z)
{
    m_x *= vector3x;
    m_y *= vector3y;
    m_z *= vector3z;
}

Vector3D Vector3D::operator-()
{
    Vector3D v;
    v.m_x = -m_x;
    v.m_y = -m_y;
    v.m_z = -m_z;
    return v;
}

Vector3D Vector3D::operator+(Vector3D other)
{
    Vector3D v;
    v.m_x = m_x + other.m_x;
    v.m_y = m_y + other.m_y;
    v.m_z = m_z + other.m_z;
    return v;
}

Vector3D Vector3D::operator-(Vector3D other)
{
    Vector3D v;
    v.m_x = m_x - other.m_x;
    v.m_y = m_y - other.m_y;
    v.m_z = m_z - other.m_z;
    return v;
}

Vector3D Vector3D::operator*(Vector3D other)
{
    Vector3D v;
    v.m_x = m_x * other.m_x;
    v.m_y = m_y * other.m_y;
    v.m_z = m_z * other.m_z;
    return v;
}

Vector3D Vector3D::operator/(Vector3D other)
{
    Vector3D v;
    v.m_x = m_x / other.m_x;
    v.m_y = m_y / other.m_y;
    v.m_z = m_z / other.m_z;
    return v;
}

bool Vector3D::operator<(Vector3D other)
{
    if (GetMagnitude() < other.GetMagnitude())
        return true;
    return false;
}

bool Vector3D::operator>(Vector3D other)
{
    if (GetMagnitude() > other.GetMagnitude())
        return true;
    return false;
}

bool Vector3D::operator<=(Vector3D other)
{
    if (GetMagnitude() <= other.GetMagnitude())
        return true;
    return false;
}

bool Vector3D::operator>=(Vector3D other)
{
    if (GetMagnitude() >= other.GetMagnitude())
        return true;
    return false;
}

bool Vector3D::operator==(Vector3D other)
{
    if (GetMagnitude() == other.GetMagnitude())
        return true;
    return false;
}

bool Vector3D::operator!=(Vector3D other)
{
    if (GetMagnitude() != other.GetMagnitude())
        return true;
    return false;
}

void Vector3D::operator=(Vector3D other)
{
    m_x = other.m_x;
    m_y = other.m_y;
    m_z = other.m_z;
}

void Vector3D::operator+=(Vector3D other)
{
    m_x += other.m_x;
    m_y += other.m_y;
    m_z += other.m_z;
}

void Vector3D::operator-=(Vector3D other)
{
    m_x -= other.m_x;
    m_y -= other.m_y;
    m_z -= other.m_z;
}

void Vector3D::operator*=(Vector3D other)
{
    m_x *= other.m_x;
    m_y *= other.m_y;
    m_z *= other.m_z;
}

void Vector3D::operator/=(Vector3D other)
{
    m_x /= other.m_x;
    m_y /= other.m_y;
    m_z /= other.m_z;
}

ostream& operator<<(ostream& out, const Vector3D& v)
{
    out << v.m_x << ", " << v.m_y << ", " << v.m_z;
    return out;
}

istream& operator>>(istream& in, Vector3D& v)
{
    cout << "Vector 2 Input" << endl << "x:";
    in >> v.m_x;

    cout << "y : ";
    in >> v.m_y;

    cout << "z : ";
    in >> v.m_z;

    return in;
}

我只是從類向量2繼承兩個成員。它們是x和y。 m_x和m_y。

Answer 1

您正在嘗試更改操作員的行為。 不要那樣做！ 常量正確性不是可選的wrt運算符。 這些是您錯誤聲明的運算符（以及應如何聲明）。

    Vector3D operator -() const;
    Vector3D operator +(const Vector3D& other) const;
    Vector3D operator -(const Vector3D& other) const;
    Vector3D operator *(const Vector3D& other) const;
    Vector3D operator /(const Vector3D& other) const;

    bool operator < (const Vector3D& other) const;
    bool operator > (const Vector3D& other) const;
    bool operator <= (const Vector3D& other) const;
    bool operator >= (const Vector3D& other) const;
    bool operator == (const Vector3D& other) const;
    bool operator != (const Vector3D& other) const;

    // non-const methods, that return mutable reference to this. 
    Vector3D& operator = (const Vector3D& other);
    Vector3D& operator += (const Vector3D& other);
    Vector3D& operator -= (const Vector3D& other);
    Vector3D& operator *= (const Vector3D& other);
    Vector3D& operator /= (const Vector3D& other);

我假設錯誤是因為它試圖在一對向量上調用operator <，但是它們都是const，所以沒有現有的operator <重載可以對值進行處理（因為它們都是const）。