Question

我正在从文件和每一行读取数据结构，但是当我尝试打印该文件时，它并不总是有效。这是我从中读取的文件：

TuniLib;Sebesta;Programming Languages;14
Sampola;Budd;Data Structures in C++;2
Sampola;Wirth;Compiler Construction;on-the-shelf
Metso;Savitch;Problem Solving with C++;8
Sampola;Sebesta;Programming Languages;3

这是我的数据结构：

struct Book {
   std::string title;
   std::string author;
   int reservations;
};

using BookVector = std::vector<Book>;
using AuthorData = std::map<std::string, BookVector>;
using Libaries = std::map<std::string, AuthorData>;

const int ON_THE_SHELF = 0;

这是我的代码：

//prints the libaries 
void print_libaries(const Libaries& libs) {
for (auto libinfo: libs) {
       std::cout << libinfo.first << std::endl;
   }         
}

//Adds the information to Libaries structure
void insert_book(Libaries& libs, const std::string& libary, const std::string& author,
             const std::string& bookname, int reservations) {
   if (libs.find(libary) == libs.end()) {
       libs.insert({libary, {}});
   }

   if(libs.at(libary).find(author) == libs.at(libary).end()) {
       libs.at(libary).insert({author, {}});
   }

   for (Book& book: libs.at(libary).at(author)) {
        if (book.title == bookname) {
              book.reservations = reservations;
              return;
        }
   }
   libs.at(libary).at(author).push_back({bookname, author, reservations});

}
//reads the information and splits the information
void read_file(std::ifstream& stream) {
   Libaries libs;
   int i;
   std::vector<std::string> parts;
   std::string line;
   while (getline(stream, line)) {
       parts = split(line, ';');
       if (parts.at(3) == "on-the-shelf") {
           i = ON_THE_SHELF;

       } else {
           i = std::stoi(parts.at(3));
       }
       insert_book(libs, parts.at(0), parts.at(1), parts.at(2), i);

   }
   for (auto libinfo: libs) {
       std::cout << libinfo.first << std::endl;
   }

}

int main() {
   Libaries libs;

   std::string file_name;
   std::cout << "Input file: ";
   std::getline(std::cin, file_name);

   std::ifstream file(file_name);

   if (not file) {
       std::cout << "Error: the input file cannot be opened." << std::endl;
       return EXIT_FAILURE;
   }

   read_file(file);

   while(true) {
       std::string command ;
       std::cout << "> ";
       std::getline(std::cin, command);

       if (command == "libaries") {
           std::cout << "test"<< std::endl;
           print_libaries(libs);
       }
   }
}

因此这是程序不会在print_libaries函数中打印库。仅当我在read_file函数中尝试时才打印它们。我认为我的结构某种程度上不记得键和值，或者它们从我的结构中删除了，但我不知道为什么。

这里也是我的拆分功能，以防万一：

std::vector<std::string> split(const std::string& s, const char delimiter, bool ignore_empty = false){
   std::vector<std::string> result;
   std::string tmp = s;

   while(tmp.find(delimiter) != std::string::npos)
   {
       std::string new_part = tmp.substr(0, tmp.find(delimiter));
       tmp = tmp.substr(tmp.find(delimiter)+1, tmp.size());
       if(not (ignore_empty and new_part.empty()))
       {
           result.push_back(new_part);
       }
   }
   if(not (ignore_empty and tmp.empty()))
   {
       result.push_back(tmp);
   }
   return result;
}

如果有人可以帮助我，将不胜感激。

打印信息时数据结构不起作用

0 个答案: