error: size in array new must have integral type [-fpermissive]

Question

我正在使用动态内存分配来创建新对象，但在我尝试编译时不断出现以下错误。我将 dimensions_ 创建为 unsigned int，所以我不确定为什么会出现此错误。

EuclideanVector.h:69:40: error: size in array new must have integral type [-fpermissive]
                         magnitude_  =  new double [dimensions_];

错误指向的代码如下：

// target constructor for delegating constructor
template <typename NUM1, typename NUM2> // any numeric types of user input for dimensions and magnitude will be static_cast to unsigned int and double respectively
EuclideanVector(const NUM1 dimensions, const NUM2 magnitude){

            // static cast to unsigned int for temp and assign dimensions_ to that
            unsigned int temp = static_cast<unsigned int>(dimensions);
            dimensions_ = new unsigned int (temp);

            // assign pointer "magnitude_" to dynamically-allocated memory of new unnamed array<double> object of size "dimensions_"
            magnitude_  =  new double [dimensions_];

            // fill the array<double> object "magnitude_" a number of "dimensions_" times, with the <double> value of "magnitude_" for each dimension
            std::fill_n(magnitude_, dimensions_, static_cast<double>(magnitude));

            updateNormal();
      }

Answer 1

dimensions_ 是一个指针，而不是 unsigned int，从 new unsigned int (temp); 返回。
你需要像 magnitude_ = new double [*dimensions_];

这样的东西

Answer 2

不能使用指针作为数组大小。

"array of size computed at run-time" 的一般解决方案是使用 std::vector。