將具有映射的抽象基類派生的對象存儲在基類指針的向量數組中

Question

我正在編寫一個使用OOP存儲學生記錄的程序。 目前，我只有兩個班級，每個單獨的課程模塊一個名為“課程”的課程，以及一個從“記錄”基礎派生的名為“物理”的學位課程類型的課程（如果算上抽象基類，則為兩個）。類。

我在程序中使用了兩個地圖。 一種是為每個單獨的記錄存儲單獨的課程，並按課程代碼對其進行排序，另一個是存儲所有記錄並按ID號對其進行排序。

我計划讓用戶輸入所有學生信息，包括代碼，將其存儲在矢量中（在代碼中稱為“ prec”），然后將矢量元素推入用於存儲所有記錄的地圖中。 代碼還遠遠沒有完成，我只是試圖運行它以查看我是否在正確的軌道上。

該代碼的生成沒有任何錯誤，但是當我嘗試運行它時，它會顯示錯誤消息：“調試斷言失敗：表達式向量下標超出范圍”。 我覺得這可能與我使用單個矢量元素調用函數以將課程存儲在地圖中的方式有​​關，但是我無法完全理解它，任何幫助將不勝感激！

這是我的文件：

頭文件：

#ifndef MY_CLASS_H // Pre-processor directives to prevent multiple definition 
#define MY_CLASS_h

#include <iostream>
#include <string>
#include <utility>
#include <map>
#include <fstream>




using std::string;
using std::ostream;
using std::map;
using std::cout;
using std::endl;
using std::cin;

namespace student_record // Defines the namespace student_record in which the classes are defined 
{
    class Course {  /* Create class Course for individual courses, is this better than incorporating
                    all the data separately into the Record class below? Class contains course name, mark achieved and mark weight and course ID */
    protected:
        string course_name;
        double course_mark; 
        int course_Id;

    public:
        Course() {course_name= "Null"; // Default constructor for null course
                  course_mark=0;
                  }

        Course(string course_namein, double course_markin, int course_Idin) {course_name=course_namein; // Parametrized constructor to create course with set name, mark, weight and course ID
                                                                                                   course_mark=course_markin;

                                                                                                   course_Id=course_Idin;}

        ~Course() {course_name.erase(0,course_name.size());}    // Destructor to delete the course name 

        // Access functions to get name, mark and weight //

        double getmark() const {return course_mark;}
        string getname() const {return course_name;}
        int getid() const {return course_Id;}

        friend ostream & operator << (ostream &os, const Course &c);        // Friend function to overload the insertion operator for courses 
    };

    class Record 
    {   // Create class Record as abstract base class for all inherited degree classes

    protected: 
        string student_name;
        int studentid;
        int years;

    public:
        Record() {student_name="Casper";
                  studentid=0;
                  years=0;}     // Default constructor for class Record, produces empty record

        Record(string name, int number, int time) {student_name=name;
                                                   studentid=number;
                                                   years=time;}  // Parametrized constructor for class Record 

        ~Record() {student_name.erase(0, student_name.size());} // Destructor to delete the student name



        virtual int getid()const=0;
        virtual int getyears()const=0;
        virtual void show_record()const=0;
        virtual void print_record(string *filename)const=0;
        virtual void degree_class()const=0;
        virtual void insert_class()=0;


        /* Virtual functions defined to be used in the derived classes (subjects ie, Physics, stamp collecting, etc...) 
        Thus the base class Record is abstract*/
    };


    class Physics: public Record
    {
    private:
        string degree_name;
        typedef map <int, Course> course_map;
        course_map modules;


        void searchdatabase (course_map &courses, int coursecode)const; // Uses iterator to search map for corresponding course to inputted key ( remember to move to function definitions)

        string get_name (const int i, course_map &temp) const{ return temp[i].getname();}
        double get_mark(const int i, course_map &temp)const{ return temp[i].getmark();} // Functions to return the mark, weight and name of a given course corresponding to inputed course code
        int getid()const{return studentid;}
        int getyears()const{return years;}
        void show_record()const;

        void print_record( string *filename) const;
        void degree_class()const;
        void insert_class();
        // Function to insert record into map


    public:
        Physics():Record(){degree_name= "Physics ";}
        Physics(string name,int Id, int time):Record( name,  Id,  time){degree_name= "Physics";}
        ~Physics() {degree_name.erase(0, degree_name.size());}


    };
}


#endif

函數定義：

#include <iostream>
#include <string>
#include <utility>
#include <map>
#include <fstream>
#include <vector>
#include "Database_header.h"

using namespace std;
using namespace student_record;

ostream & student_record::operator<< (ostream &os, const Course &c)
{
    os<< "Course code" << c.course_Id << " \n Course name: " <<c.course_name << " \n Mark " << c.course_mark <<endl;
    return os;
}

// Function to insert classes //
void Physics::insert_class()
{

    int courseid;
    string coursename;
    double mark;
    cout << " Enter course code " << endl;
    cin >> courseid;
    cout << " \n Enter course name " << endl;
    cin >> coursename;
    cout << " \n Enter mark achieved " << endl;
    cin >> mark;

    Course temp (coursename, mark, courseid);

    modules.insert(pair<int, Course>(courseid, temp));

}

void Physics::searchdatabase(course_map &courses, int coursecode) const // Function to search for specific course mark based on course code, need to modify this!!!!
                                                                        //takes in a map as its argument, although i suppose can use student.modules? 

        {
            course_map::iterator coursesIter;
            coursesIter=courses.find(coursecode);
            if(coursesIter != courses.end())
            {
                cout << " Course Code " << 
                coursecode << " corresponds to " <<
                coursesIter ->second << endl;
            }
            else { cout << " Sorry, course not found " << endl; }
        }

void Physics::print_record( string *filename) const // Function for printing record to the file
{
    ofstream myoutputfile;
    myoutputfile.open(*filename,ios::app);
    if(!myoutputfile.good())
        {
        // Print error message and exit
        cerr<<"Error: file could not be opened"<<endl;
        }

    if(myoutputfile.good())
    {
    myoutputfile << "Student name: " << student_name << endl
                 << "\n Student ID: "  << studentid << endl
                 << "\n Year: " << years << endl;
                  course_map::iterator modulesiter; // Iterator to print out courses using overloaded << function (I think?)
    for(modulesiter==modules.begin();modulesiter!=modules.end();modulesiter++)
        {
            myoutputfile<<modulesiter->second << endl;
        }
    }


}

void Physics::show_record() const // Function for showing specific student record on screen ( with iterator for map of courses)
{
    cout << "Student name: " << student_name;
    cout << "\n Student ID: " << studentid;
    cout << "\n Years on course: " << years;
    cout << "\n Courses and grades: ";
    course_map::iterator modulesiter; // Iterator to print out courses using overloaded << function (I think?)
    for(modulesiter==modules.begin();modulesiter!=modules.end();modulesiter++)
        {
            cout<<modulesiter->second << endl;
        }

}

void Physics::degree_class()const
{
    double temp;
    vector<double> dynarr; // Create a vector array to store the grades extracted from the course map for each student
    course_map::iterator modulesiter; 
    for(modulesiter==modules.begin();modulesiter!=modules.end();modulesiter++) // Iterate through map and push values into each vector
        {
            Course ghost;
            ghost=modulesiter->second;
            dynarr.push_back(ghost.getmark());
        }
    double sum(0);
    for(int i(0);i<=dynarr.size();i++)
    {
        sum+=dynarr[i];
    }

    temp=sum/dynarr.size();

    if( temp>=40 && temp <=49.9)
    {
        cout << "The student has achieved a 3rd class degree with an average of: \n "
             << temp;
    }

    else if( temp>=50 && temp <=59.9)
    {
        cout << "The student has achieved a 2:2 degree with an average of: \n "
             << temp;
    }

    else if( temp>=60 && temp <=69.9)
    {
        cout << "The student has achieved a 2:1 degree with an average of: \n "
             << temp;
    }

    else if( temp>=70)
    {
        cout << "The student has achieved a 1st class degree with an average of: \n "
             << temp;
    }

    else { cout << "The student has failed the degree " << endl;}


}

和主要的cpp文件：

#include <iostream>
#include <utility>
#include <map>
#include <iomanip>
#include <vector>
#include "Database_header.h"
#include <fstream>

using namespace std;
using namespace student_record;

void main()
{
    // Create map to store students with ID keys //

    string full_name;
    int id;
    int time;
    string degree_name;

    vector<Record*> prec;
    // Vector of base class pointers to store all the different records first. No need to specify length as it is a vector! (Advantage over dynamic array?)
    char student_test('y'); // Condition for adding students to the record //
    int q(0);
    while (student_test=='y' || student_test=='Y')
    {
         // Counter for while loop


        cout<< " \n Please enter the student name " << endl;
        getline(cin, full_name);

        // Enter student name, check it is a string? //

        cout<< "\n Please enter student ID " << endl;
        cin >> id;

        // Check if not integer or number, if not need error message //

        cout << "\n Please enter the number of years on the course " << endl;
        cin >> time;

        // Check if not integer or number, if not need error message //

        cout<< "\n Please enter degree type " << endl;
        cin>>degree_name;

        if(degree_name=="Physics" || degree_name=="physics")    // create object of appropriate derived class ( Physics, Chem, Maths, Bio)
        {
            prec.push_back(new Physics(full_name, id, time));
        }

        char class_test('y'); // test condition for class insertion loop

        while(class_test=='y') // Add courses+marks into course map
        {
            cout << " \n Add classes to student record " << endl;
            prec[q]->insert_class();
            cout << " \n Add another class? Y/N" << endl;
            cin>>class_test;
        }

        cout << "Enter another student? Y/N " << endl;
        cin >> student_test;

        if(student_test=='N' && student_test=='n')
        {
            cout << "\n Thank you for using the student database, Goodbye !" << endl;
        }

        q++; // increment counter, to keep track of of vectors of base class pointers, and also be able to output number of students

    }

    // Next insert all records into map //
    typedef map<int, Record*> studentlist;
    studentlist studentmap;

    for(int i(0); i<=prec.size(); i++)
    {
        studentmap.insert(pair<int, Record*> (prec[i]->getid(), prec[i]));
    }

}

非常感謝！

Answer 1

for(int i(0); i<=prec.size(); i++)
{
    studentmap.insert(pair<int, Record*> (prec[i]->getid(), prec[i]));
}

應該是我<prec.size（）而不是<=