可变参数模板和 std::array 意外行为

Variadic template and std::array unexpected behaviour

我可以编译,但我在运行以下代码中遇到问题(我将其最小化):

#include <iostream>
#include <array>


template<int N>
class Selector {

public:

    template <typename... Args>
    Selector(int x, Args... args) noexcept {
        integers[sizeof...(Args)] = x;
        std::cout << "integers[" << sizeof...(Args) << "]=" << integers[sizeof...(Args)] << std::endl;  // OK

        Selector(args...);
    }

    Selector(int x) noexcept {
        integers[0] = x;
        std::cout << "integers[0]=" << integers[0] << std::endl;    // OK
    }


    void print_num(int i) const {
        std::cout << "integers[" << i << "]=" << integers[i] << std::endl;
    }

private:
    std::array<int, N> integers;
};

int main() {
    Selector<3> x(5, 10, 15);

    x.print_num(2); // OK
    x.print_num(1); // KO
    x.print_num(0); // KO

}

输出为:

integers[2]=5
integers[1]=10
integers[0]=15
integers[2]=5
integers[1]=1016039760
integers[0]=22034

很明显,数组的前两个单元格在对象初始化后有垃圾编号。我怀疑我以某种方式破坏了堆栈,但我无法弄清楚 why/where...

构造函数中的语句Selector(args...);,只是构造了一个临时对象,该对象立即被销毁;它与当前对象无关。

我想你想要 delegating constructor (C++11 起):

template <typename... Args>
Selector(int x, Args... args) noexcept : Selector(args...) {
//                                     ^^^^^^^^^^^^^^^^^^^
    integers[sizeof...(Args)] = x;
    std::cout << "integers[" << sizeof...(Args) << "]=" << integers[sizeof...(Args)] << std::endl;  // OK
}

LIVE