用map的单词转换以及文件打开的相对路径问题

Posted 2020-12-02 flyingziming

#include <iostream>
#include <map>
#include <fstream>
#include <sstream>
#include <string>
using namespace std;

map<string,string> buildMap(ifstream & map_file)
{
    map<string,string> trans_map;
    string key;
    string value;
    while(map_file>>key && getline(map_file,value))//! first word : key,the rest : value
    {
        if(value.size()>1){
            trans_map[key] = value.substr(1);
        }else{
            throw runtime_error("no rule for" + key);
        }
    }
    return trans_map;
}

const string &
transform(const string& word, const map<string,string> & m)
{
    auto map_it = m.find(word);
    if(map_it != m.cend())
    {
        return map_it->second;
    }else{
        return word;
    }
}
void word_transform(ifstream &map_file, ifstream &input)
{
    auto trans_map= buildMap(map_file);
    string text;
    while(getline(input,text))
    {
        std::istringstream stream(text);
        string word;
        bool firstWord = true;
        while(stream >> word)
        {
            if(firstWord) firstWord = false;
            else cout << " ";
            cout<< transform(word,trans_map);
        }
        cout<<endl;
    }
}

int main()
{
    ifstream ifs_map("word_transformation_bad.txt"),
        ifs_content("given_to_transform.txt");
    if (ifs_map && ifs_content)
        word_transform(ifs_map, ifs_content);
    else
        std::cerr << "can‘t find the documents." << std::endl;
//    map<string,int> msi = { {"sdji",2},{"bdsdad",3}};
//    auto c= msi.find("sdji");
//
//    auto lb = msi.lower_bound("bdsda");
//    cout<<lb->second;
//    cout << "Hello world!" << endl;
    return 0;
}

 来自C++Primer，我对文件读写不是特别熟悉，ifstream的文件打开可以相对路径可以绝对路径，这里是一个相对路径的版本，只要和主程序放在同一个文件夹就可以了

 向下就直接 /

    ifstream ifs_map("data/word_transformation_bad.txt"),
        ifs_content("data/given_to_transform.txt");

向上一级就 ../ 

    ifstream ifs_map("../data/word_transformation_bad.txt"),
        ifs_content("../data/given_to_transform.txt");