std::initializer_list<T>

std::initializer_list<T>提供了以下接口：

size_t size() const noexcept;
const T* begin() const noexcept;
const T* end() const noexcept;

通过std::initializer_list<T>可以实现大括号初始化对象。也可以实现类似于动态类型的效果。

#include <iostream>
#include <initializer_list>
#include <vector>

using namespace std;

class Test {
    vector<int> list;
public:
    Test(std::initializer_list<int> args) {
        list.insert(list.end(), args.begin(), args.end());
    }
    void print() {
        for (auto &it : list) {
            cout << it << ' ';
        }
        cout << endl;
    }
    vector<int> &get() {
        return list;
    }
};

class TestArray {
    vector<Test> list;
public:
    TestArray(std::initializer_list<Test> args) {
        list.insert(list.end(), args.begin(), args.end());
    }
    void print() {
        for (auto &it : list) {
            for (auto &x : it.get()) {
                cout << x << ' ';
            }
            cout << endl;
        }
    }
};

int main()
{
    Test t{1, 2, 3, 4, 5, 6};
    t.print();
    TestArray t2{ {1, 2},{3},{4, 5, 6},{7, 8, 9, 10} };
    t2.print();
    int n;
    cin >> n;
    return 0;
}