• C++primer 练习12.27


    // 12_27.cpp : 定义控制台应用程序的入口点。
    //
    
    #include "stdafx.h"
    #include<iostream>
    #include<memory>
    #include<string>    
    #include<vector>
    #include<fstream>
    #include<sstream>
    #include<map>
    #include<set>
    using namespace std;
    
    //提前声明类QueryResult,在书中说必须提前声明,然而vs2015中
    //仅声明友元类亦可
    class QueryResult;
    
    class TextQuery
    {
        //友元类的声明
        friend class QueryResult;
    public:
        //构造函数
        TextQuery(ifstream &is);
        //返回查询的结果
        QueryResult query(string s);
    
    private:
        //用智能指针来保存数据,实现共享
        shared_ptr<vector<string>> vecPtr;
        shared_ptr<map<string, set<unsigned>>> mapPtr;
    };
    
    //TextQuery的构造函数
    TextQuery::TextQuery(ifstream &is)
    {
        //用来暂存每一行的字符串
        string word;
        //记录行数
        unsigned lineNum = 0;
        //对两个智能指针进行值初始化
        vecPtr = shared_ptr<vector<string>>(new vector<string>());
        mapPtr = shared_ptr<map<string, set<unsigned>>>(new map<string, set<unsigned>>());
        while (getline(is, word))
        {
            //将每一行保存在类中
            vecPtr->push_back(word);
            istringstream iss(word);
            string str;
            while (iss >> str)
            {
                //将单词所在的行数记录下来
                (*mapPtr)[str].insert(lineNum);
            }
            ++lineNum;
        }
    }
    
    class QueryResult
    {
    public:
        //QueryResult的构造函数,vecPtr实现共享
        QueryResult(TextQuery &tq, string &s) :vecPtr(tq.vecPtr) 
        { 
            //mapPtr指针的值初始化
            mapPtr = shared_ptr<map<string, set<unsigned>>>(new map<string, set<unsigned>>());
            //将要查询的单词的结果保存下来
            mapPtr->insert(pair<string, set<unsigned>>(s, (*tq.mapPtr)[s])); 
        }
        //有缘函数,实现输出
        friend ostream& print(ostream&,const QueryResult &qr);
    private:
        shared_ptr<vector<string>> vecPtr;
        shared_ptr<map<string, set<unsigned>>> mapPtr;
    };
    
    //QueryResult的友元函数,实现输出
    ostream& print(ostream &os,const QueryResult &qr)
    {
        //输出这个单词出现了多少次
        os << (*qr.mapPtr).cbegin()->first << " occurs " << (*qr.mapPtr).cbegin()->second.size() <<
            ((*qr.mapPtr).cbegin()->second.size() > 1 ? "times" : "time") << endl;
        //输出单词所在的行数,和这一行的字符串
        for (auto &e : qr.mapPtr->cbegin()->second)
            os << "(line " << e << " )  " << (*qr.vecPtr)[e] << endl;
        return os;
    }
    
    //实现查询的函数
    QueryResult TextQuery::query(string s)
    {
        return QueryResult(*this, s);
    }
    
    void runQueries(ifstream &infile)
    {
        TextQuery tq(infile);
        while (true)
        {
            cout << "enter word to look for,or q to quit: ";
            string s;
            if (!(cin >> s) || s == "q")break;
            print(cout, tq.query(s)) << endl;
        }
    }
    
    int main()
    {
        ifstream ifs("D:\file\12_27.txt");
        if (!ifs)
        {
            cerr << "open file failed!" << endl;
            exit(-1);
        }
        runQueries(ifs);
        return 0;
    }
  • 相关阅读:
    密码学中矩阵相关计算
    系统调用
    用户空间栈&系统空间栈
    drupal重置管理员密码
    中断&异常
    再谈文件描述符
    linux下libpcap抓包分析
    模拟LRU算法&通道处理算法
    [转载] Mysql常用命令行大全
    [转载] php java交互 php/java bridge
  • 原文地址:https://www.cnblogs.com/csudanli/p/5375671.html
Copyright © 2020-2023  润新知