看不看的懂123456789

Question

#include <iostream>
#include <fstream>
#include <vector>
#include <stdio.h>
#include <string>

using namespace std;

class CacheStack
{
private:
    int capacity;        // max length
    int cur_length;        // length
    string file_path;    //cache file

    vector<string> readFromFile();
    void writeToFile(vector<string>);
    void add_node(string);    // add node to file
    void del_last_node();    // delete last node
    void del_first_node();    // delete first node
    string get_last_node();    // get the last node

public:
    CacheStack(int, string);

    bool empty();        // cache empty
    int size();            // max_length
    int length();        // current length
    string pop();        // pop and delete last node
    int push(string);    // push node 
};
CacheStack::CacheStack(int max_len = 10, string file_path = "D:/msd_reissue")
    :capacity(max_len), file_path(file_path)
{
    //init :chech file
    fstream fs;
    fs.open(file_path, ios::in);
    if (!fs.is_open())    
    {
        // file not exists
        // create file
        fs.open(file_path, ios::out);
        fs << 0;    // write node number to file
    }
    fs >> cur_length;
    fs.close();
}

vector<string> CacheStack::readFromFile()
{
    vector<string> vect;
    string line;
    fstream fs;
    fs.open(file_path, ios::in);
    fs >> cur_length;

    // read all node 
    while (getline(fs, line))
    {
        if (line != "")
        {
            vect.push_back(line);
        }
    }
    cur_length = vect.size();
    fs.close();
    return vect;
}

void CacheStack::writeToFile(vector<string> vect)
{
    // clean file
    fstream fs;
    fs.open(file_path, ios::trunc);
    fs.close();

    // write vect to file
    fs.open(file_path, ios::out);
    fs << vect.size() ;
    cur_length = vect.size();
    for (vector<string>::iterator it = vect.begin(); vect.end() != it; it++)
    {
        fs << endl<< *it;
    }
    fs.close();
}


void CacheStack::add_node(string node)
{
    vector<string> vect = readFromFile();
    vect.push_back(node);
    writeToFile(vect);
}


void CacheStack::del_first_node()
{
    vector<string> vect = readFromFile();
    vect.erase(vect.begin());
    writeToFile(vect);
}


void CacheStack::del_last_node()
{
    vector<string> vect = readFromFile();
    if (0 != vect.size())
    {
        vect.erase(vect.end() - 1);
        writeToFile(vect);
    }
}
string CacheStack::get_last_node()
{
    vector<string> vect = readFromFile();
    if (0 == vect.size())
    {
        throw string("stack empty!get last failed!");
    }
    string back= vect.back();
    vect.erase(vect.end() - 1);
    writeToFile(vect);
    return back;
}


int CacheStack::size()
{
    return capacity;
}

int CacheStack::length()
{
    return cur_length;
}

bool CacheStack::empty()
{
    return (0 == cur_length);
}

int CacheStack::push(string node)
{
    if (cur_length == capacity)
    {
        del_first_node();
    }
    add_node(node);
    return cur_length;
}

string CacheStack::pop()
{
    string str="";
    try {
        str = get_last_node();    // throw error when empty
    }
    catch (string str) {
        cout << "pop failed:stack empty! \n";
    }
    return str;
}

int main()
{
    string file_path = "D:/msd_reissue";
    CacheStack cs(10,file_path);
    int choose;            // input choose
    string data;        // input data
    bool flag = true;    // while flag
    while (flag)
    {
        cout << "1:push node\n2:pop node\n3:exit\n";
        cout << "Please choose func:";
        cin >> choose;
        switch (choose)
        {
            case 1:    // push
                cout << "Please input node(enter 'exit' to end):\n";
                while(true)
                {
                    cin >> data;
                    if ("exit" == data) 
                    {
                        break;
                    }
                    cs.push(data);
                }
    
                break;
            case 2:    // pop
                data = cs.pop();
                cout << "pop:" << data << endl;
                break;

            case 3:    // exit
                flag = false;
                break;
        }
    }
    return 0;
}

Answer 1

所以你想问什么？秀你本身吗？还是看不懂？有注释在上面！