“错误：没有匹配的调用函数”。 [英] "error: no matching function for call to"

问题描述

我当时在键盘上，我试图使用C ++来提高自己的技能。我以前从未使用过模板，因此尝试研究如何使用它们。下面的代码是结果，但不幸的是，它不起作用。我确实尝试寻找问题的解决方案，但是由于我在使用模板方面没有太多经验，因此无法在问题和其他问题之间建立任何联系。因此，我决定寻求帮助。

I was on codepad and I was trying to build up my skills using C++. I'd never used templates much before, so I tried looking into how to use them. The code below is the result, and unfortunately, it does not work. I did try to search for solutions to my problem, but since I don't have much experience using templates, I couldn't make any connections between my problem and other problems. So, I decided to ask for help.

template <class A>
class Vector2 {
public:
    A x,y;
    Vector2(A xp, A yp){
        this->x = xp;
        this->y = yp;
    }
};

template <class B, class A>
class rayToCast {
public:
    rayToCast(B angle, Vector2<A> origin, Vector2<A> point1, Vector2<A> point2){
        this->RAngle = angle;
        this->Point1 = point1;
        this->Point2 = point2;
    }
private:
    B RAngle;
    Vector2<A> point1,point2;
};

int main(){
    rayToCast<short int, float> ray(45, Vector2<float>(0.0, 0.0), Vector2<float>(-10.0, -3.0), Vector2<float>(5.0, 7.0));
    return 0;
}

这是输出：

t.cpp: In constructor 'rayToCast<B, A>::rayToCast(B, Vector2<A>, Vector2<A>, Vector2<A>) [with B = short int, A = float]':
t.cpp:26:   instantiated from here
Line 14: error: no matching function for call to 'Vector2<float>::Vector2()'
compilation terminated due to -Wfatal-errors.

我们将不胜感激。

推荐答案

rayToCast 构造函数尝试初始化 point1 和 point2 ，方法是调用 Vector2 的默认构造函数。

The rayToCast constructor tries to initialize point1 and point2 by calling Vector2's default constructor. But it doesn't have one.

您必须为vector类提供默认的构造函数，或者显式初始化 rayToCast 。一种方法是这样进行：

You either have to provide a default constructor for the vector class, or explicitly initialize the members of rayToCast. One way is to do like this:

rayToCast(B angle, Vector2<A> origin, Vector2<A> point1, Vector2<A> point2)
   : RAngle(angle), point1(point1), point2(point2)
{ }

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