C++11中的{}与std::initializer_list深度解析

struct A {
	int _x;
	int _y;
};
int main() 
{
	int arr1[] = { 1,2,3,4,5,6 };
	int arr2[] = { 0 };
	A a = { 3,4 };
	return 0;
}

#include <iostream>
#include <vector>
using namespace std;
struct A {
	int _x;
	int _y;
};
class Student {
public:
	Student(const string& name, const int id = 0, const int age = 0)
		:_name(name)
		,_id(id)
		,_age(age){}
	Student(const Student& s) 
		:_name(s._name)
		,_id(s._id)
		,_age(s._age){ }
private:
	string _name;
	int _id;
	int _age;
};
int main() 
{
	// C++98中的{}
	int arr1[] = { 1,2,3,4,5,6 };
	int arr2[] = { 0 };
	A a = { 3,4 };
	//C++11中的{}
	//内置类型初始化
	int a = { 1 };
	//自定义类型初始化
	Student stu1 = { "WangPeng", 20251117, 19 };
	//这里stu2引用的是{ "YiYi", 20258888, 18 }临时变量
	const Student& stu2 = { "YiYi", 20258888, 18 };
	//只有{}初始化，才可以省略=
	double num{ 3.14159 };
	Student s{ "ZhangWei", 20236666, 22 };
	vector<Student> students;
	students.push_back(stu1);
	students.push_back(Student{ "WangPeng", 20251117, 19 });
	//相比有名对象和匿名对象传参,{}更加方便
	students.push_back({ "WangPeng", 20251117, 19 });
	return 0;
}

vector<int> = {1， 2， 3， 4}；

auto il = {98, 99, 100};

#include <iostream>
#include <vector>
#include <map>
using namespace std;
int main()
{
	std::initializer_list<int> mylist;
	mylist = { 23,24,25,26,27 };
	int i = 0;
	//my_list中只存了两个首尾指针(在64位环境下大小均为8个字节)
	cout << sizeof(mylist) << endl;//输出16 
	//首尾指针地址与变量i地址接近 说明该数组存储在栈上
	cout << mylist.begin() << endl;
	cout << mylist.end() << endl;
	cout << &i << endl;
	//直接构造
	vector<int> v1({ 1,2,3,4,5 });
	//构造临时对象->临时对象拷贝给v2->优化为直接构造
	vector<int> v2 = { 6,7,8,9,10 };
	const vector<int>& v3 = { 11,22,33,44,55 };
	//pair类型的{}初始化 + map的initializer_list构造
	map<string, string> dict = { {"a","一个"},{"stack","栈"},{"queue","队列"} };
	//initializer_list赋值可以这样写
	v1 = { 111,222,333,444,555 };
	return 0;
}