#include<iostream>
#include<vector>
using namespace std;

#include<string>
void test_vector1()
{
	vector<int> v1;
	vector<int> v2(10, 0); //开辟10个整型的空间,并将每个空间初始化为0
	for (auto i : v2)
	{
		cout << i << " ";
	}
	cout << endl;

	string s("hello world");
	vector<int> v3(s.begin(), s.end()); //用迭代器区间来初始化v3
	vector<int>::iterator it = v3.begin();
	while (it != v3.end())
	{
		cout << *it << " ";
		++it;
	}
	cout << endl;

}
void test_vector2()
{
	vector<int> v;
	size_t sz = v.capacity();
	cout << "mark v grow:" << endl;
	for (int i = 0; i < 100; i++)
	{
		v.push_back(i);
		if (sz != v.capacity())
		{
			sz = v.capacity();
			cout << "capcaity changed:" << sz << endl;
		}
	}
	//大概是1.5倍扩容
}
void test_vector3()
{
	vector<int> v;
	//v.reserve(100); //仅仅只是将capacity开辟为100,但是size还是为0
	v.resize(100); //size变为100,capacity也开辟为100(或100以上)
	for (size_t i = 0; i < 100; i++)
	{
		v[i] = i;
	}
	//注意:上面如果是用reserve来扩容,虽然有容量,但是不能通过v[i]这种形式给数组赋值
	//因为[]重载里面有assert断言size不能为0,所以即使开辟了空间,也是不能通过[]去给数组赋值的
	for (auto e : v)
	{
		cout << e << " ";
	}
	cout << endl;
}
void test_vector4()
{
	vector<int> v;
	//max_size()的作用是返回容器在理论上或实现上能容纳的最大元素数量
	cout << v.max_size() << endl;

	v.push_back(1);
	v.push_back(2);
	v.push_back(3);
	v.push_back(4);
	cout << v.size() << endl;
	cout << v.capacity() << endl;

	cout << "-------------------------" << endl;
	//reserve会将capacity扩容为跟所给参数一样大,但是不会改变size
	//注意;如果所给参数小于当前的size时,capacity会改变成跟size一样大
	v.reserve(100);
	cout << v.size() << endl;
	cout << v.capacity() << endl;

	cout << "-------------------------" << endl;
	//将size调整为跟所给参数一样大,但是不改变空间容量capacity
	v.resize(3);
	cout << v.size() << endl;
	cout << v.capacity() << endl;

	cout << "-------------------------" << endl;
	//当容器元素数量size远小于其预分配容量capacity时,
	//调用shrink_to_fit()会尝试将capacity降低至与size相等,释放多余的内存空间‌
	v.shrink_to_fit();
	cout << v.size() << endl;
	cout << v.capacity() << endl;
}
void test_vector5()
{
	vector<int> v;
	v.push_back(1);
	v.push_back(2);
	v.push_back(3);
	v.push_back(4);

	v.insert(v.begin(), 0);
	for (auto e : v)
	{
		cout << e << " ";
	}
	cout << endl;

	auto it1 = find(v.begin(), v.end(), 3);
	if (it1 != v.end())
	{
		v.insert(it1, 30);  //注意:it1这个迭代器在insert使用以后会失效
	}
	for (auto e : v)
	{
		cout << e << " ";
	}
	cout << endl;

	auto it2 = find(v.begin(), v.end(), 3);
	if (it2 != v.end())
	{
		v.erase(it2); //注意:it2这个迭代器在erase后会失效
	}
	for (auto e : v)
	{
		cout << e << " ";
	}
	cout << endl;

	cout << v.size() << endl;
	cout << v.capacity() << endl;
	v.clear(); //clear是用来清理掉有效数据的,但是不会释放空间capacity
	cout << v.size() << endl;
	cout << v.capacity() << endl;
}
int main()
{
	test_vector1();
	return 0;
}