双向链表的存储读出数据修改的程序//为何崩溃,该如何处理

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

struct table{
    table():next(NULL),prev(NULL){};
    table(int id_t,char* name_t,int age_t):
        id(id_t),name(name_t),age(age_t),next(NULL),prev(NULL){}
    int id;
    char* name;
    int age;
    table* next;
    table* prev;
};

table* ifRead(char* file)//读出文件函数实现
{
    table* head=NULL,*memory=NULL,*cur=NULL,*tail=NULL;
    ifstream iff(file);
    iff.seekg(0,ios::beg);
    char str[8]="";
    int count=0;
    while(iff.getline(str,sizeof(str),' '))//读出操作与存入链表中
        if(++count==1)
        {
            memory = new table;
            if(head==NULL&&tail==NULL)
            {
                head=memory;
                tail=memory;
                int temp=0;
                int i=0;
                while(str[i]!='\0')
                {
                    str[i]-=48;
                    temp=temp*10+str[i];
                    i++;
                }
                memory->id=temp;
            }
            else
            {
                tail->next=memory;
                memory->prev=tail;
                tail=memory;
                int temp=0;
                int i=0;
                while(str[i]!='\0')
                {
                    str[i]-=48;
                    temp=temp*10+str[i];
                    i++;
                }
                memory->id=temp;
            }

        }
        else if(count==2)
        {
            memory->name=str;
        }
        else if(count==3)
        {
            int temp=0;
            int i=0;
            while(str[i]!='\0')
            {
                str[i]-=48;
                temp=temp*10+str[i];
                i++;
            }
            memory->age=temp;
            count=0;
        }
    iff.close();
    return head;
}

void revise(table* head,char* fname)//修改完毕并存入文件中
{
    cout<<"input student's id that you want to midfy"<<endl;
    int id_modfiy;
    cin>>id_modfiy;
    table* cur=head;
    while(cur!=NULL)
    {
        if(cur->id==id_modfiy)
        {
            cout<<"1.Do you want to modify the student's id"
                <<"2.Do you want to modify the student's name"
                <<"3.Do you want to modify the student's age"
                <<"4.Do you want to modify the student's whole information"
                <<endl;
            int choice;
            cin>>choice;
            switch(choice)
            {
                case 1:cin>>cur->id;break;
                case 2:cin>>cur->name;break;
                case 3:cin>>cur->age;break;
                case 4:cin>>cur->name>>cur->id>>cur->age;break;
            }
        }
        cur=cur->next;
    }
}

int main()
{
    
    char fname[10]="";
    cout<<"input student's information table file name"<<endl;
    cin>>fname;
    table* head=ifRead(fname);
    revise(head,fname);
}

    if(++count==1)
        {
            memory = new table;
            if(head==NULL&&tail==NULL)
            {
/*为什么不初始化memory节点内部的next和prev指针？？？name指针为什么不申请内存存放数据，而是指向了一个你用来存放临时数据的buff呢？？还是就是与这个if匹配的else有何作用呢？我发现好像根本就不可能进入到这个else里面。*/
                head=memory;
                tail=memory;
                int temp=0;
                int i=0;
                while(str[i]!='\0')
                {
                    str[i]-=48;
                    temp=temp*10+str[i];
                    i++;
                }
                memory->id=temp;
            }
            else
            {
                tail->next=memory;
                memory->prev=tail;
                tail=memory;
                int temp=0;
                int i=0;
                while(str[i]!='\0')
                {
                    str[i]-=48;
                    temp=temp*10+str[i];
                    i++;
                }
                memory->id=temp;
            }

        }