使用终止程序的指针在数组中输入字符串

Question

我不熟悉编程和基本的学生管理系统。系统首先要求用户输入数据。 6件事； id、姓名、大学、系、学期和 gpa。数据输入工作正常。数据输入完成后，会出现一个包含三个选项的菜单。一种是创建一个新的学生档案。在这种情况下，当用户输入学生姓名时，程序会突然终止。我在每一个有意义的地方都使用了 cin.ignore，但同样的问题也发生了。任何帮助，将不胜感激。谢谢你。代码如下。 注意：我不允许使用结构和/或向量。

#include<iostream>
#include<string>
using namespace std;

int main()
{
cout<<"------------------------------------- Welcome to student management system! ----------------------------------------------"<<endl;
cout<<"------------------------------------------------DATA INPUT----------------------------------------------"<<endl;
cout<<"Enter the number of students you want to enroll: ";
int size;
int n=0;
int counter=0;
cin>>size;

int *student_ids=new int[size];
int *semester=new int[size];
float *cgpa=new float[size];
string *names=new string[size];
string *uni=new string[size];
string *dept=new string[size];

int *ptr_id,*ptr_semester;
string *ptr_names,*ptr_uni,*ptr_dept;
float *ptr_cgpa;

cout<<"Enter their ids: "<<endl;
ptr_id=student_ids;
for(int i=0;i<size;i++)
{
    cin>>*ptr_id;
    ptr_id++;
}

ptr_names=names;
cout<<"Enter their names: "<<endl;
cin.ignore();
for(int i=0;i<size;i++)
{

    getline(cin,*ptr_names);
    ptr_names++;
}

ptr_uni=uni;
cout<<"Enter their Universities: "<<endl;
for(int i=0;i<size;i++)
{
    getline(cin,*ptr_uni);
    ptr_uni++;
}

ptr_dept=dept;
cout<<"Enter their departments: "<<endl;
for(int i=0;i<size;i++)
{

    getline(cin,*ptr_dept);
    ptr_dept++;
}

ptr_semester=semester;
cout<<"Enter their semester: "<<endl;
for(int i=0;i<size;i++)
{
    cin>>*ptr_semester;
    ptr_semester++;
}

ptr_cgpa=cgpa;
cout<<"Enter the GPA: "<<endl;
for(int i=0;i<size;i++)
{
    cin>>*ptr_cgpa;
    ptr_cgpa++;
}
cout<<"-----------------------------------------------DATA INPUT COMPLETE----------------------------------------------------------- "<<endl;

int choice;
char again='y';
while(again=='y'||again=='Y')
{

cout<<"Press 1 to Create a Student Profile"<<endl;
cout<<"Press 2 to Search a Student"<<endl;
cout<<"Press 3 to Delete a Student record"<<endl;
cin>>choice;

switch(choice)
{
    case 1: //CREATING STUDENT PROFILE

        cout<<"Enter the number of profiles you want to create: ";
        cin>>n;
        cout<<"Enter ID(s): ";
        for(int i=size;i<size+n;i++)
        {
            cin>>*ptr_id;
            ptr_id++; 
        }
        cout<<student_ids[1];
        cout<<student_ids[0];

        cout<<"Enter name(s): ";
        cin.ignore();
        for(int i=size;i<size+n;i++)
        {

            getline(cin,*ptr_names);
            cin.ignore();
            ptr_names++;
        }
        cout<<names[1]<<endl;

        cout<<"Enter University: ";
        for(int i=size;i<size+n;i++)
        {

            getline(cin,*ptr_uni);
            ptr_uni++;
        }

        cout<<"Enter Department(s): ";
        for(int i=size;i<size+n;i++)
        {
            getline(cin,*ptr_dept);
            ptr_dept++;
        }
        cout<<dept[2]<<endl;

        cout<<"Enter semester(s): ";
        for(int i=size;i<size+n;i++)
        {
            cin>>*ptr_semester;
            ptr_semester++;
        }

        cout<<"Enter CGPA: ";
        for(int i=size;i<size+n;i++)
        {
            cin>>*ptr_cgpa;
            ptr_cgpa++;
        }

    cout<<"------------------------------------------------SUCCESS-------------------------------------------------------------";
    cout<<endl;
    break;

    case 2: //SEARCHING
        int searching_method;
        cout<<"Press 1 to search by ID."<<endl;
        cout<<"Press 2 to list all students."<<endl;
        cin>>searching_method;

        switch(searching_method)
        {
            case 1: //SEARCHING BY ID
                cout<<"Enter the student ID: ";
                int search;
                cin>>search;
                for(int i=0;i<size+n;i++)
                {
                    if(student_ids[i]==search)
                    {
                        counter++;
                        cout<<"Name: "<<names[i]<<endl;
                        cout<<"University: "<<uni[i]<<endl;
                        cout<<"Department: "<<dept[i]<<endl;
                        cout<<"Semester: "<<semester[i]<<endl;
                        cout<<"CGPA: "<<cgpa[i]<<endl;
                        break;
                    }
                }
                if(counter==0)
                {
                    cout<<"No student found!"<<endl;
                }
                break;

            case 2: //LIST OF ALL STUDENTS
                for(int i=0;i<size+n;i++)
                {
                    cout<<"Student ID: "<<student_ids[i]<<endl;
                    cout<<"Name: "<<names[i]<<endl;
                    cout<<"University: "<<uni[i]<<endl;
                    cout<<"Department: "<<dept[i]<<endl;
                    cout<<"Semester: "<<semester[i]<<endl;
                    cout<<"CGPA: "<<cgpa[i]<<endl; 
                    cout<<endl;
                    cout<<endl;                       
                }
                break;
        }

    //case 3: //DELETEING A STUDENT ID
}
}
system("pause");
return 0;
}

Answer 1

因此，在程序开始时，您要求用户输入学生人数的大小。当您完成初始化“数据库”中的学生时。现在，对于您尝试添加的下一个学生，您在 ptr_names 数组中没有更多空间，因为您已在初始化步骤中填充了它。

你可以做什么：

-如果您知道可以创建的最大学生数，请将大小设置为该数字

-更好的解决方案是将 std::vector 用于动态大小的容器。

为了使您的代码更好，您可以创建这样的学生结构或班级

struct student{
    int id;
    int semester;
    float cgpa;
    std::string name;
    std::string uni;
    std::string dept;
}

这样，您可以使用如下所示的向量存储所有学生：

std::vector<student> all_students;

这里有更多关于向量的信息 https://en.cppreference.com/w/cpp/container/vector