从文本文件读取到结构向量，但文本文件行的长度不同 [英] reading from text file to struct vector, but text file lines are of different length

问题描述

我正在尝试从学生的文本文件中读取内容，并将每一行分配给struct数据成员.

I am trying to read from a text file of students and assign each line to a struct data member.

文本文件结构如下:

Name,Student code, Ability,Consistency,Program name:Subject list

文件中有两名学生:

Average Ant,204932,50,5,Short course:1
Brilliant Bison,234543,80,3,Bachelor of Bounciness:2,5,3

除了最后一部分(主题列表)，学生之间的长度不同，我可以毫无问题地阅读所有信息. 我该如何编写代码，以便如果一个学生只有1个像平均蚂蚁这样的科目，我可以将其推入subjectList向量，但是如果他们有3个像出色的野牛一样，我仍然可以毫无问题地将它们全部推入?

I can read all of the information to a struct no problem except for the last part(subject list),that are of varying length between students. How can I write code so that if a student only has 1 subject like average ant I can push it into the subjectList vector but if they have 3 like brilliant bison I can still push them all in no problem?

我的代码:

struct Student
{
    string name;
    int code;
    int ability;
    int consistency;
    string programName;
    vector<int> subjectList;
};

void createStudents(string fileName)
{
    string tempSubjectId;
    int subjectId;

    //temp variable to then use to convert them to int.
    string codeTemp, abilityTemp, consistencyTemp;

    std::ifstream studentFile(fileName);

    //A new student data member is created
    Student newStudent;


    if(studentFile.is_open() && studentFile.good())
    {
        cout << " " << endl;
        cout << "---Reading from Students---" << endl;
        while(getline(studentFile,newStudent.name, ','))
        {

            //we go get each value which is delimited by a comma and one by a colon
            //getline(studentFile, newStudent.name, ',');

            //To convert the strings to an int, the string is given to a temporary variable
            //Then the temporary variable is parsed to an int using stoi and the code datamember from the struct is assign to that new int
            getline(studentFile, codeTemp, ',');
            newStudent.code = stoi(codeTemp);

            getline(studentFile, abilityTemp, ',');
            newStudent.ability = stoi(abilityTemp);

            getline(studentFile, consistencyTemp, ',');
            newStudent.consistency = stoi(consistencyTemp);

            getline(studentFile, newStudent.programName, ':');

//want to push ints into subject list here.


            //The new struct data member is added to the vector and returned for further use.
            studentList.push_back(newStudent);
        }
        //file is then closed
        studentFile.close();```

推荐答案

在主循环中，将整行读取为std::string，然后使用std::istringstream解析每一行，并使用内部循环读取主题整数，例如:

In your main loop, read an entire line into a std::string, then use a std::istringstream to parse each line, using an inner loop to read the subject ints, eg :

#include <string>
#include <sstream>
#include <fstream>
#include <vector>

struct Student
{
    std::string name;
    int code;
    int ability;
    int consistency;
    std::string programName;
    std::vector<int> subjectList;
}; 

std::vector<Student> studentList;

void createStudents(std::string fileName)
{
    std::string tempLine;

    //temp variable to then use to convert them to int.
    std::string tempStr;

    std::ifstream studentFile(fileName);

    if (studentFile.is_open())
    {
        std::cout << " " << std::endl;
        std::cout << "---Reading from Students---" << std::endl;

        while (std::getline(studentFile, tempLine))
        {
            std::istringstream iss(tempLine);

            //A new student data member is created
            Student newStudent;

            //we go get each value which is delimited by a comma and one by a colon

            std::getline(iss, newStudent.name, ',');

            //To convert the strings to an int, the string is given to a temporary variable
            //Then the temporary variable is parsed to an int using stoi and the code datamember from the struct is assign to that new int
            std::getline(iss, tempStr, ',');
            newStudent.code = std::stoi(tempStr);

            std::getline(iss, tempStr, ',');
            newStudent.ability = std::stoi(tempStr);

            std::getline(iss, tempStr, ',');
            newStudent.consistency = std::stoi(tempStr);

            std::getline(iss, newStudent.programName, ':');

            // push ints into subject list
            while (std::getline(iss, tempStr, ',')) {
                newStudent.subjectList.push_back(std::stoi(tempStr));
            } 

            //The new struct data member is added to the vector and returned for further use.
            studentList.push_back(std::move(newStudent));
        }

        //file is then closed
        studentFile.close();
    }
}

这篇关于从文本文件读取到结构向量，但文本文件行的长度不同的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！