动态数组 vector容器_动态数组容器

动态扩展机制：扩展时不是续接新空间，直接找一个更大的空间
vector的迭代器支持随机访问

#include <vector>
 #include <algorithm>
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1.构造函数
无参构造，只定义未初期化

void test ()
{
	vector<vector<int>>vip;
	vector<int>v1;
	vector<int>v2;
	vector<int>v3;
	vector<int>v4;
	
	for (int i = 0; i < 4; i++) {
		v1.push_back(i + 1);
		v2.push_back(i + 5); 
		v3.push_back(i + 9); 
		v4.push_back(i + 13);
	}
	vip.push_back(v1);
	vip.push_back(v2);
	vip.push_back(v3);
	vip.push_back(v4);
	for (vector<vector<int>>::iterator it = vip.begin(); it != vip.end(); it++) {
		for (vector<int>::iterator vit = (*it).begin(); vit != (*it).end(); vit++) {
			cout << *vit << " ";
		}
		cout<< endl;
	}
}
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for (vector<vector<int>>::iterator it = vip.begin(); it != vip.end(); it++) {
		vector<int> vip2((*it).begin(), (*it).end()); 
		showInfo(vip2);
		}
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vector<int> vip3(10, 100);
	showInfo(vip3);
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vector<int> vip4(vip3);
	showInfo(vip4);
void showInfo(vector<int>& v)
{
	for (vector<int>::iterator it = v.begin(); it != v.end(); it++) {
		cout << *it << " ";
		}
	cout << endl;
}
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2.赋值操作

vector<int>v1;
for (int i = 0; i < 10; i++)
{
	v1.push_back(256);
}
showInfo(v1);

vector <int>v2;
v2 = v1;
showInfo(v2);

vector<int>v3;
v3.assign(v2.begin(), v2.end());
showInfo(v3);

vector<int>v4;
v4.assign(10, 65535);
showInfo(v4);
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3.插入和删除
void test01()
{
vectorv1;
//尾插
v1.push_back(10);
v1.push_back(20);
v1.push_back(30);
v1.push_back(40);
v1.push_back(50);

//遍历
showInfo(v1);
//尾删
v1.pop_back();
showInfo(v1);
//插入  第一个参数是迭代器
v1.insert(v1.begin(), 100);
showInfo(v1);
v1.insert(v1.begin(), 2, 1000);
showInfo(v1);

//删除 参数也是迭代器
v1.erase(v1.begin());
showInfo(v1);

//清空
//v1.erase(v1.begin(), v1.end());
v1.clear();
showInfo(v1);
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}

4.数据存取
void test()

{
	vector<int>v1;
	v1.push_back(pow(2,1));
	v1.push_back(pow(2,2));
	v1.push_back(pow(2,3));
	v1.push_back(pow(2,4));
	v1.push_back(pow(2,5));
	cout << "第一个元素为： " << v1.front() << endl;
	cout << "最后一个元素为： " << v1.back() << endl;
}
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5.容器互换

void test()
{
	vector<int>v1;
	vector<int>v2;
	v1.push_back(pow(2,1));
	v1.push_back(pow(2,2));
	v1.push_back(pow(2,3));
	v1.push_back(pow(2,4));
	v1.push_back(pow(2,5));
	v2.push_back(pow(2,6));
	v2.push_back(pow(2,7));
	v2.push_back(pow(2,8));
	v2.push_back(pow(2,9));
	v2.push_back(pow(2,10));
	for (int i = 0; i < v1.size(); i++)
	{
		cout<< v1[i] << " ";
	}
	cout << endl;
	for (int i = 0; i < v2.size(); i++)
	{
		cout<< v2.at(i) << " ";
	}
	cout << endl;
	v1.swap(v2);
		for (int i = 0; i < v1.size(); i++)
	{
		cout<< v1[i] << " ";
	}
	cout << endl;
	for (int i = 0; i < v2.size(); i++)
	{
		cout<< v2.at(i) << " ";
	}
	cout << endl;
}
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6.预留空间
/

    int num = 0; //统计开辟次数
	int * p = NULL;
	***//v.reserve(100000);***
	for (int i = 0; i < 100000; i++)
	{
		v.push_back(i);

		if (p != &v[0])
		{
			p = &v[0];
			num++;
		}
	}

	cout << "num = " << num << endl;
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加入v.reserve(100000);

7.容器大小

void test()
{
	vector<int>v1;
	vector<int>v2;
	v1.push_back(pow(2,1));
	v1.push_back(pow(2,2));
	v1.push_back(pow(2,3));
	v1.push_back(pow(2,4));
	v1.push_back(pow(2,5));
	if (v1.empty()) //为真 代表容器为空
	{
		cout << "v1为空" << endl;
	}
	else
	{
		cout << "v1不为空" << endl;
		cout << "v1的容量为： " << v1.capacity() << endl;
		cout << "v1的大小为： " << v1.size() << endl;
	}

	//重新指定大小
	v1.resize(15 , 100); //利用重载版本，可以指定默认填充值，参数2
	showInfo(v1);//如果重新指定的比原来长了，默认用0填充新的位置

	v1.resize(1);
	showInfo(v1); //如果重新指定的比原来短了，超出部分会删除掉
}
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