用整数的初始化列表初始化长双精度数的向量 [英] Initialize Vector of Long Doubles with Initialization List of Ints

问题描述

假设我有一个简单的课:

Suppose I have a simple class:

class Pvector
{
  private:
  std::vector<long double> point_list;

  public:
  Pvector(std::initializer_list<long double> coords) : point_list(coords)
  {}
  Pvector(std::initializer_list<int> coords) : point_list(coords)
  {}
};

这不会编译，因为以long double类型为模板的std::vector不能从以int类型为模板的初始化列表进行初始化.但是，这很不方便，因为删除了第二个构造函数后，我无法在代码中执行以下操作:

This will not compile because the std::vector templated on type long double cannot initialize itself from an initialization list templated on type int. This is rather inconvenient, however, because with the second constructor removed, I cannot do the following in my code:

Pvector piece_movement({E.X - S.X, E.Y - S.Y, E.Z - S.Z});

这是因为我的算术运算得到的结果类型是int类型.因此，我似乎处于一个难题之中.我希望能够将整数直接传递到Pvector的构造函数中，但是我仍然希望point_list是long double类型，并且(以某种方式)使用传入的整数进行初始化.关于这样做吗?

This is because the resultant type from my arithmetic operations is of type int. So I seem to be in a conundrum. I'd like to be able to pass integers directly into the constructor for Pvector, but I still want point_list to be of type long double and (somehow) be initialized with the integers I pass in. How might I go about doing this?

推荐答案

解决方案1 ​​

您可以删除第二个构造函数，但仍然可以使用

You can remove the second constructor and still be able to construct PVector using

 Pvector v2{1, 2};

示例:

#include <initializer_list>
#include <vector>

class Pvector
{
  private:
  std::vector<long double> point_list;

  public:
  Pvector(std::initializer_list<long double> coords) : point_list(coords)
  {}
};

int main()
{
   Pvector v1{1.0, 2.0};
   Pvector v2{1, 2};
}

解决方案2

在Pvector中使用模板构造函数，并使用std::vector的构造函数，该构造函数需要两个迭代器来初始化point_list.

Use a template constructor in Pvector and the use the constructor of std::vector that takes two iterators to initialize point_list.

#include <initializer_list>
#include <vector>

class Pvector
{
  private:
  std::vector<long double> point_list;

  public:

  // This is not necessary any more.
  // Pvector(std::initializer_list<long double> coords) : point_list(coords){}

  template <typename T>
  Pvector(std::initializer_list<T> coords) : point_list(coords.begin(), coords.end()){}
};

int main()
{
   Pvector v1{1.0, 2.0};
   Pvector v2{1, 2};
}

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