vector容器基本用法

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

void printV(vector<int> &v1)     //用来输出容器
{
    for (vector<int>::iterator it = v1.begin(); it != v1.end(); it++)  //begin指在开始元素， end指在结束元素的后面
    {
        cout << *it << " ";
    }
    cout << endl;
}

void f1()
{
    vector <int> v1;
    cout << "length: " << v1.size() << endl;    //用size()求长度
    v1.push_back(1);
    v1.push_back(3);
    v1.push_back(5);
    cout << "length: " << v1.size() << endl;

    cout << "头部元素:" << v1.front() << endl;      //获取头部元素
    while (v1.size() > 0)
    {
        cout << "尾部元素: " << v1.back() << endl;      //获取尾部元素
        v1.pop_back();                //删除尾部元素
    }

    //修改头部和尾部元素的值
    v1.front() = 11;
    v1.back() = 55;
    cout << "头部元素:" << v1.front() << endl;
    cout << "尾部元素: " << v1.back() << endl;
}

//vector的定义和迭代器遍历
void f2()
{
    vector <int> v1(10);
    for (int i = 0; i < 10; i++)
    {
        v1[i] = i + 1;
    }
    //正向遍历
    for (vector<int>::iterator it = v1.begin(); it != v1.end(); it++)  //begin指在开始元素， end指在结束元素的后面
    {
        cout << *it << " ";
    }
    cout << endl;

    //逆向遍历
    for (vector<int>::reverse_iterator rit = v1.rbegin(); rit != v1.rend(); rit++)
    {
        cout << *rit << " ";
    }
}

//vector 删除 插入
void f3()
{
    vector <int> v1(10);
    for (int i = 0; i < 10; i++)
    {
        v1[i] = i + 1;
    }

    //删除前3个元素
    v1.erase(v1.begin(), v1.begin() + 3);
    printV(v1);

    //在头部删除一个元素
    v1.erase(v1.begin());   //在头部删除一个元素

    //根据元素的值删除
    for (vector<int>::iterator it = v1.begin(); it != v1.end(); )
    {
        if (*it == 9)
            it = v1.erase(it);       //当删除迭代器所指向的元素的时候，erase删除函数会让it自动下移
        else                         //同时返回下一个有效的迭代器
            it++;
    }
    printV(v1);

    //插入
    v1.insert(v1.begin(),100);
    v1.insert(v1.end(), 200);
    printV(v1);
}

int main()
{
    f3();
    return 0;
}