C++，stl，vector容器详解

目录

 1.vector基本概念

2.vector的创建

3.vector赋值操作

4.vector容量和大小的操作

5.vector容器的插入和删除

6.vector容器的数据存取

 7.vector互换容器

8.vector容器预留空间

---

 1.vector基本概念

2.vector的创建

#include
using namespace std;

int main()
{
	vector v1;
	v1.push_back(5);
	v1.push_back(3);
	v1.push_back(7);
	
	for(vector::iterator i = v1.begin(); i != v1.end(); i++)
		cout << *i << ' ';
		
	cout << endl;
		
	vector v2(v1.begin(),v1.end());
	for(vector::iterator i = v2.begin(); i != v2.end(); i++)
		cout << *i << ' ';
		
	cout << endl;
	
	vector v3(5,100);
	//第一个为个数，第二个为赋值
	for(vector::iterator i = v3.begin(); i != v3.end(); i++)
		cout << *i << ' ';
	
	cout << endl;
	
	vector v4(v3);
	//拷贝构造
	for(vector::iterator i = v4.begin(); i != v4.end(); i++)
		cout << *i << ' ';
		
	return 0;
}

3.vector赋值操作

#include
using namespace std;

void print(vector &v)
{
	for(vector::iterator i = v.begin(); i != v.end(); i++)
		cout << *i << ' ';
		
	cout << endl;
}
int main()
{
	vector v1;
	v1.push_back(5);
	v1.push_back(3);
	v1.push_back(7);
	print(v1);
	
	vector v2;
	v2 = v1;
	print(v2);
	
	vector v3;
	v3.assign(v1.begin(),v1.end());
	print(v3);
	
	vector v4;
	v4.assign(3,100);
	print(v4);
	
	return 0;
}

4.vector容量和大小的操作

#include
using namespace std;

void print(vector &v)
{
	for(vector::iterator i = v.begin(); i != v.end(); i++)
		cout << *i << ' ';
		
	cout << endl;
}
int main()
{
	vector v1;
	cout << v1.empty() << endl;
	v1.push_back(5);
	v1.push_back(3);
	v1.push_back(7);
	cout << v1.empty() << endl;
	cout << endl << v1.capacity() << endl;
	cout << endl << v1.size() << endl << endl;
	
	v1.resize(8,10);
	//将长度变为8，用10填充新的位置，（新的位置默认填充是0）
	//如果重新指定的size比原来短，多余的会被删除
	print(v1);
	
	return 0;
}

5.vector容器的插入和删除

#include
using namespace std;

void print(vector &v)
{
	for(vector::iterator i = v.begin(); i != v.end(); i++)
		cout << *i << ' ';
		
	cout << endl;
}
int main()
{
	vector v1;
	
	v1.push_back(5);
	v1.push_back(3);
	v1.push_back(7);
	
	print(v1);
	
	v1.pop_back();
	print(v1);
	
	v1.insert(v1.begin(),2,100);
	//第一个参数是迭代器
	print(v1);
	
	v1.erase(v1.begin());
	print(v1);
	
	v1.erase(v1.begin(),v1.end());
	print(v1);
	
	v1.clear();
	//全部清空的操作
	return 0;
}

6.vector容器的数据存取

#include
using namespace std;

void print(vector &v)
{
	for(vector::iterator i = v.begin(); i != v.end(); i++)
		cout << *i << ' ';
		
	cout << endl;
}
int main()
{
	vector v1;
	
	v1.push_back(5);
	v1.push_back(3);
	v1.push_back(7);
	
	for(int i = 0; i < v1.size(); i ++)
	{
		cout << v1[i] << ' ';
	}
	cout << endl;
	
	for(int i = 0; i < v1.size(); i++)
	{
		cout << v1.at(i) << ' ';
	}
	cout << endl;
	
	cout << v1.front() << endl;
	cout << v1.back() << endl;
	
	return 0;
}

 

 7.vector互换容器

#include
using namespace std;

void print(vector &v)
{
	for(vector::iterator i = v.begin(); i != v.end(); i++)
		cout << *i << ' ';
		
	cout << endl;
}
int main()
{
	vector v1;
	
	v1.push_back(5);
	v1.push_back(3);
	v1.push_back(7);
	
	vector v2;
	v2.push_back(1);
	v2.push_back(1);
	v2.push_back(1);
	
	print(v1);
	print(v2);
	
	v1.swap(v2);
	
	print(v1);
	print(v2);
	
	//如果我们创建了一个vectorv,让它存了很多东西
	//之后又用resize把它的大小变小了，但它的capacity没有改变，还是很大
	//使用vector(v).swap(v)可以巧妙的收缩内存
	//这行代码创建了一个大小为v的vector容器的匿名对象与v进行了交换
	//匿名对象在下一行后内存就会被释放
	
	return 0;
}

8.vector容器预留空间

#include
using namespace std;

void print(vector &v)
{
	for(vector::iterator i = v.begin(); i != v.end(); i++)
		cout << *i << ' ';
		
	cout << endl;
}
int main()
{
	vector v1;
	
	v1.push_back(5);
	v1.push_back(3);
	v1.push_back(7);
	v1.push_back(1);
	v1.push_back(2);
	
	cout << v1.capacity() << endl;
	cout << v1.size() << endl;
	
	v1.reserve(100);
	
	cout << v1.capacity() << endl;
	cout << v1.size() << endl;
	
	return 0;
}