c++ - 如何使用 initializer_ist 在构造函数中初始化动态数组？

Question

我正在尝试使用 C++ 中的 initialize_list 在构造函数中初始化动态数组。我怎样才能做到这一点？

#include <cstdlib> 
#include <initializer_list>
#include <iostream>
#include <utility>

using namespace std;

class vec {
private:
    // Variable to store the number of elements contained in this vec.
    size_t elements;
    // Pointer to store the address of the dynamically allocated memory.
    double *data;

public:
    /*
      * Constructor to create a vec variable with the contents of 'ilist'.
    */
    vec(initializer_list<double> ilist);
}

int main() {
    vec x = { 1, 2, 3 };  // should call to the constructor 
    return 0;
}

Answer 1

initializer_list 有 size 方法，它告诉你有多少元素必须由 new 分配，所以它可以是:

vec(initializer_list<double> ilist)
{
    elements = ilist.size();
    data = new double[ ilist.size() ];
    std::copy(ilist.begin(),ilist.end(),data);
}