从文件读取时出现浮点异常

Question

程序应该从 2 个文件（author.dat 和 citation.dat）中读取并将它们保存到地图和集合中；首先它毫无问题地读取了引文列表，然后它似乎正确地读取了作者和 在它遍历整个列表后 (author.dat) 一个 浮点异常 出现..不太明白为什么

似乎发生在 author.cpp 的作者列表

的构造函数中

author.cpp:

#include <fstream>
#include <iostream>
#include "authors.h"

using namespace std;

AuthorList::AuthorList(char *fileName) {
    ifstream s (fileName);
    int idTemp;
    int nrTemp;
    string nameTemp;

    try {
        while (true){
            s >> idTemp >> nrTemp >> nameTemp;
            cout << idTemp << " " << nrTemp << " " << nameTemp << " test_string";
            authors.insert(std::make_pair(idTemp,Author(idTemp,nrTemp,nameTemp)));
            if (!s){
                cout << "IF-CLAUSE";
                throw EOFException();
            }
             cout << "WHILE-LOOP_END" << endl;
        }
    } catch (EOFException){}
}

author.h:

#ifndef CPP_AUTHORS_H
#define CPP_AUTHORS_H

#include <iostream>
#include <map>
#include <string>
#include "citations.h"

class Author {
public:
    Author (int id, int nr, std::string name) :
            articleID(id),
            authorNR(nr),
            authorName(name){}

    int getArticleID() const {
        return articleID;
    }

    std::string getAuthorName() const {
        return authorName;
    }

private:
    int articleID;
    int authorNR;
    std::string authorName;
};

class AuthorList {
public:
    AuthorList(char *fileName);

    std::pair<std::multimap<int,Author>::const_iterator, std::multimap<int,Author>::const_iterator> findAuthors(int articleID) {
        return authors.equal_range(articleID);
    }

private:
    std::multimap<int,Author> authors;
};

#endif //CPP_AUTHORS_H

programm.cpp:

#include <iostream>
#include <cstdlib>
#include "citations.h"
#include "authors.h"
#include "authorCitation.h"

using namespace std;

int main(int argc, char *argv[]){
    CitationList *cl;
    AuthorList *al;

    //check if argv array has its supposed length
    if (argc != 4){
        cerr << "usage: programm article.dat citation.dat author.dat";
        return EXIT_FAILURE;
    }

    //inserting citation.dat and author.dat in corresponding lists (article.dat not used)
    cl = new CitationList(argv[2]);
    al = new AuthorList(argv[3]);
    try {
        AuthorCitationList *acl;
        acl->createAuthorCitationList(al,cl);
        acl->printAuthorCitationList2File("authorcitation.dat");
    } catch (EOFException){
        cerr << "something went wrong while writing to file";
        return EXIT_FAILURE;
    }
    return EXIT_SUCCESS;
}

所有文件： https://drive.google.com/file/d/0B734gx5Q_mVAV0xWRG1KX0JuYW8/view?usp=sharing

Answer 1

我敢打赌，问题是由以下代码行引起的：

AuthorCitationList *acl;
acl->createAuthorCitationList(al,cl);

您正在使用未初始化的指针调用成员函数。我建议将第一行更改为：

AuthorCitationList *acl = new AuthorCitationList;

向构造函数添加任何必要的参数。

当你这样做的时候，也改变读取数据的循环。你有：

while (true){
    s >> idTemp >> nrTemp >> nameTemp;
    cout << idTemp << " " << nrTemp << " " << nameTemp << " test_string";
    authors.insert(std::make_pair(idTemp,Author(idTemp,nrTemp,nameTemp)));
    if (!s){
        cout << "IF-CLAUSE";
        throw EOFException();
    }
    cout << "WHILE-LOOP_END" << endl;
}

当您这样做时，您最终会在到达行尾后添加一次数据。另外，您似乎将最后一行放在了错误的位置。在我看来，它应该在 while 循环之外。

您可以使用：

while (true){
    s >> idTemp >> nrTemp >> nameTemp;

    // Break out of the loop when reading the
    // data is not successful.
    if (!s){
        cout << "IF-CLAUSE";
        throw EOFException();
    }
    cout << idTemp << " " << nrTemp << " " << nameTemp << " test_string";
    authors.insert(std::make_pair(idTemp,Author(idTemp,nrTemp,nameTemp)));
}
cout << "WHILE-LOOP_END" << endl;

您可以使用以下方法进一步简化它：

while (s >> idTemp >> nrTemp >> nameTemp){
   cout << idTemp << " " << nrTemp << " " << nameTemp << " test_string";
   authors.insert(std::make_pair(idTemp,Author(idTemp,nrTemp,nameTemp)));
}
cout << "WHILE-LOOP_END" << endl;

从文件读取时出现浮点异常

Floating Point Exception while reading from file

c++

fstream

iostream

multimap

ifstream