vector

创建一个vector对象,并赋值:

#include "stdafx.h"
#include<iostream>
#include<vector>
#include<algorithm>
using namespace std;
int main()
{
    int n,i;
    cin >> n;
    vector<int> v(n);//创建一个vector对象,大小为n
    for (i = 0; i < n; i++)
        cin >> v[i];//赋值
    for (int i = 0; i < n; i++)
        cout << v[i] << " ";//输出vector里面的值
    return 0;
}

初始化vector元素的值:

vector<int>(10,0)//大小为10,初始化为0

将数组里的值放到vector里:

#include<iostream>
#include<vector>
#include<algorithm>
using namespace std;
int main()
{
    int a[] = { 11,13,19,23,27 };
    vector<int> v(a, a + 5);//将a[0]到a[4]的值放入vector里
    for (int i = 0; i < v.size(); i++)
        cout << v[i] << " ";
    return 0;
}

从vector的尾部插入或取出元素:

#include<iostream>
#include<vector>
#include<algorithm>
using namespace std;
int main()
{
    vector <int> v;
    v.push_back(1);//插入元素
    v.push_back(2);
    v.pop_back();//取出元素
    for (int i = 0; i < v.size(); i++)
    cout << v[i] << " ";
    return 0;
}

用迭代器访问vector的元素:

#include<iostream>
#include<vector>
#include<algorithm>
using namespace std;
int main()
{
    vector <int> v;
    v.push_back(1);//插入元素
    v.push_back(2);
    v.push_back(3);
    v.push_back(4);
    vector<int>::iterator i, iend;//迭代器定义两个指向vector里元素的指针
    iend = v.end();
    for ( i = v.begin(); i!=v.end(); i++)
    cout << *i << " ";
    return 0;
}

在任意位置插入vector元素:

#include<iostream>
#include<vector>
#include<algorithm>
using namespace std;
int main()
{
    vector <int> v;
    v.push_back(1);//插入元素
    v.push_back(2);
    v.push_back(3);
    v.push_back(4);
    vector<int>::iterator i, iend;
    v.insert(v.begin(), 11);//在头之前插入11
    v.insert(v.end(), 11);//在尾之前插入11
    for ( i = v.begin(); i!=v.end(); i++)
    cout << *i << " ";
    return 0;
}

 

利用erase删除vector元素:

// 测试.cpp : 定义控制台应用程序的入口点。
//

#include "stdafx.h"

#include<iostream>
#include<vector>
#include<algorithm>
class my {
public:
    char*name;
    int age;
    my(char*name, int age)
    {
        this->name = name;
        this->age = age;
    }
    ~my() {};
};
int main()
{
    using namespace std;
    my* pdog =new my("dog", 1);
    my* pmonkey = new my("pmonkey", 1);
    my* pchicken =new my("pchicken", 1);
    my* psnake = new my("psnake", 1);
    vector<my*> v;
    v.push_back(pdog);//将类地址放入容器
    v.push_back(pmonkey);
    v.push_back(pchicken);
    v.push_back(psnake);
    delete pmonkey;
    v.erase(v.begin() + 1);
    vector<my*>::iterator i, iend;//iterator 定义一个容器指针
    iend = v.end();
    for (i = v.begin(); i != iend; i++)
    {
        cout << (*i)->name << " " << (*i)->age << endl;
    }
        v.clear();
        return 0;
}

反向遍历vector的元素:

#include<iostream>
#include<vector>
#include<algorithm>
using namespace std;
int main()
{
    vector <int> v;
    v.push_back(1);//插入元素
    v.push_back(2);
    v.push_back(3);
    v.push_back(4);
    vector<int>::reverse_iterator i, riend;
    riend = v.rend();//vector尾
    for ( i = v.rbegin(); i!=v.rend(); i++)//rbegin是vector头
    cout << *i << " ";
    return 0;
}

两个vector容器元素交换,直接用swap(v1,v2);

判断vector是否为空:

#include<iostream>
#include<vector>
#include<algorithm>
using namespace std;
int main()
{
    vector <int> v;
    v.push_back(1);//插入元素
    v.push_back(2);
    v.push_back(3);
    v.push_back(4);
    if (v.empty())//为空返回true
        cout << "yes";
    else
        cout << "no";
    return 0;
}

系统所允许的vector容器的最大元素:

cout << v.max_size();

当前vector所容纳的元素个数:

cout << v.size();

vector容器首元素:

cout << v.front();

vector容器末元素:

cout<<v.back();