initializer_list

1 构造函数场景

class P {
public:
    P(int a, int b) {
        std::cout << "int, int" << std::endl;
    }

    P(std::initializer_list<int> initList) {
        std::cout << "initializer_list" << std::endl;
    }
};

调用：

P p(1, 2);
P q{1, 2};
P r{1, 2, 4};
P s = {1, 2};

int, int
initializer_list
initializer_list
initializer_list

2 算法场景

min({1, 2, 3});
max({1, 2, 3});

源码

  // N2722 + DR 915.
  template<typename _Tp>
    _GLIBCXX14_CONSTEXPR
    inline _Tp
    min(initializer_list<_Tp> __l)
    { return *std::min_element(__l.begin(), __l.end()); }

  template<typename _Tp, typename _Compare>
    _GLIBCXX14_CONSTEXPR
    inline _Tp
    min(initializer_list<_Tp> __l, _Compare __comp)
    { return *std::min_element(__l.begin(), __l.end(), __comp); }

  template<typename _Tp>
    _GLIBCXX14_CONSTEXPR
    inline _Tp
    max(initializer_list<_Tp> __l)
    { return *std::max_element(__l.begin(), __l.end()); }

  template<typename _Tp, typename _Compare>
    _GLIBCXX14_CONSTEXPR
    inline _Tp
    max(initializer_list<_Tp> __l, _Compare __comp)
    { return *std::max_element(__l.begin(), __l.end(), __comp); }