24.迭代器(流迭代器,正向,反向迭代器,分配器,存储迭代器)

#include <iostream>
#include <vector>
#include <algorithm>
#include <iterator>
#include <fstream>
#include <deque>
#include <string>
#include <memory>
using namespace std;

//流迭代器
void main1()
{
    //vector<int> v{ 1,2,3,4,5,6,7,8,9 };
    ////流迭代器,可以输出到屏幕,也可以输出到文件
    //copy(v.begin(), v.end(), ostream_iterator<int>(cout, "  "));

    //写入到文件
    //ofstream fout("1.txt");
    ////写入到文件再加入"
"
    //ostream_iterator<int> it_tofile(fout,"
");
    //copy(v.begin(), v.end(), it_tofile);
    //fout.close();

    //system("1.txt");

    ifstream fin("1.txt");
    ofstream fout("2.txt");

    //读取迭代器
    istream_iterator<string> it_fromfile(fin);
    //写入迭代器
    ostream_iterator<string> it_tofile(fout);

    //从开始到结束复制到it_tofile中
    copy(it_fromfile, istream_iterator<string>(), it_tofile);

    fin.close();
    fout.close();
    
    system("2.txt");
    cin.get();
}

//正反向迭代器
void main2()
{
    vector<int> v{ 1,3,4,5,6,7,8,9 };
    //读写正向迭代
    for (auto ib = v.begin(), ie = v.end(); ib != ie; ib++)
    {

    }
    //只读正向迭代
    for (auto ib = v.cbegin(), ie = v.cend(); ib != ie; ib++)
    {

    }
    //读写反向迭代器
    for (auto ib = v.rbegin(), ie = v.rend(); ib != ie; ib++)
    {

    }
    //只读反向迭代器
    for (auto ib = v.rbegin(), ie = v.rend(); ib != ie; ib++)
    {

    }
    cin.get();
}

//正向,反向,随机插入迭代器
void main3()
{
    deque<int> myd{ 1,2,3,4,5 };

    //正向插入迭代器 位置在头部
    front_insert_iterator<deque<int>> it(myd);
    //反向插入迭代器 位置在尾部
    back_insert_iterator<deque<int>> its(myd);
    //随机插入迭代器 位置在随机位置
    insert_iterator<deque<int>> itss(myd, myd.begin() + 3);
    //反向迭代器
    reverse_iterator <deque<int>::iterator> rb(myd.end());
    reverse_iterator <deque<int>::iterator> re(myd.begin());
    //通过反向迭代器反向输出
    copy(rb, re, ostream_iterator<int>(cout, " "));

    *it = 1000;

    for (auto i : myd)
    {
        cout << i << endl;
    }
    cin.get();
}

class A
{
public:
    int i;

public:
    A(int num):i(num)
    {
        cout << "  A()" << endl;
    }
    ~A()
    {
        cout << "~A()" << endl;
    }
};

void main()
{
    //分配器(不会调用构造)
    allocator<A> alloc;
    A *p = alloc.allocate(10);
    //存储迭代器
    raw_storage_iterator<A*, A> rsi(p);
    //保存临时对象,作用区域完了就销毁
    for (int i = 0; i < 10; i++)
    {
        *rsi++ = A(i);
    }

    for (int i = 0; i < 10; i++)
    {
        cout << (int)((*p++).i) << endl;
    }

    //手动调用析构
    for (int i = 0; i < 10; i++)
    {
        alloc.destroy(p+i);
    }
    
    //alloc.deallocate(p, 10);
    cin.get();
}