解构 c++ 类运算符重载和构造函数初始化列表

Question

你能帮助重写这个类吗？ 即（没有构造函数初始化列表和浮点运算符重载） 或解释它是如何工作的

class HigPassFilter
{
public:
    HigPassFilter(float reduced_frequency)
        : alpha(1 - exp(-2 * PI*reduced_frequency)), y(0) {}

    float operator()(float x) {
        y += alpha * (x - y);
        return x - y;
    }
    int myfunc(bool x) { return 1; }

private:
    float alpha, y;
};

Answer 1

我将解释这是如何工作的：

class HigPassFilter
{
public:
    // Constructor of the class, with one parameter.
    HigPassFilter(float reduced_frequency)
    // initializer list initializes both data members of the class,
    // 'alpha' will be set to the result of '1 - exp(-2 * PI*reduced_frequency)'
    // and 'y' will be set to 0
        : alpha(1 - exp(-2 * PI*reduced_frequency)), y(0)
   // the body of the constructor is empty (good practice)
   {}

   // An overload of operator(), which performs a mathematical operation.
   // It will increment 'y' by 'alpha * (x - y)' and
   // return the difference of 'x' and 'y'
   float operator()(float x) {
        y += alpha * (x - y);
        return x - y;
    }

    // a simple function that returns always 1 and
    // will not used its parameter, causing an unused warning (bad practice)
    int myfunc(bool x) { return 1; }

private:
    // private data members
    float alpha, y;
};

在What is this weird colon-member (“ : ”) syntax in the constructor? 中了解更多信息。初始化列表是 C++ 的一个非常重要的特性，所以我建议你花一些时间来学习它们。大多数时候，你会在初始化列表中初始化你的数据成员——这就是为什么这个特性仍然存在的原因。

延伸阅读：Why override operator()?