错误：“Vector2D＆amp;”类型的非const引用的无效初始化来自'Vector2D'类型的右值

Question

这是代码，CodeBlocks表示错误在线上shwon：

bool SoccerTeam::isPassSafeFromOpponent(Vector2D    from,
                                        Vector2D    target,
                                        const PlayerBase* const receiver,
                                        const PlayerBase* const opp,
                                        double       PassingForce)const
{
    Vector2D ToTarget = target - from;
    Vector2D ToTargetNormalized = Vec2DNormalize(ToTarget);

    Vector2D LocalPosOpp = PointToLocalSpace(opp->Pos(),
                                             ToTargetNormalized,
                                             ToTargetNormalized.Perp(),
                                             from); // *** ERROR ***

错误讯息：

error: invalid initialization of non-const reference of type 'Vector2D&'
from an rvalue of type 'Vector2D'`

Answer 1

问题在于第3个参数，您尝试将Vector2D :: Perp（）函数的返回值作为参考传递。 （同样适用于第一个参数，但我猜这是一个const Vector2D＆amp;，所以它可能不会哭。）尝试以下内容：

bool SoccerTeam::isPassSafeFromOpponent(Vector2D    from,
                                        Vector2D    target,
                                        const PlayerBase* const receiver,
                                        const PlayerBase* const opp,
                                        double       PassingForce)const
{
    Vector2D ToTarget = target - from;
    Vector2D ToTargetNormalized = Vec2DNormalize(ToTarget);
    Vector2D ToTargetNormalizedPerp = ToTargetNormalized.Perp();

    Vector2D LocalPosOpp = PointToLocalSpace(opp->Pos(),
                                             ToTargetNormalized,
                                             ToTargetNormalizedPerp,
                                             from);