内存到底哪出了错？

Question

题目描述

我的代码在运行一部分后会意外终止，我知道是内存出现了问题，但到底是哪句话出了错？

这是我们学校的一道练习实验题

相关代码

#ifndef ADDRESS_BOOK_H
#define ADDRESS_BOOK_H
#include <iostream> 
using std::cin;
using std::cout;
using std::endl;
using std::string;
struct address
{
    string name;
    long long phone_number;
    long long classroom;
    long long dormitory;
};
class book
{
protected:
    address* a = NULL;
    int listsize;
    int arraylength;
public:
    book();
    book(const book& a);//复制构造函数；
    ~book();
    void insert(book &a);
    void _delete(book& a,string c);
    void compile(book& a,string c);
    bool find(const book& a,string c);
    void print(const book& a,int n);
};
#endif
book::book()
{
    listsize = 0;
    arraylength = 50;
    a = new address[arraylength];
    for (int i = 0; i < arraylength;i++)
    {
        a[i].classroom = 0; a[i].dormitory = 0; a[i].phone_number = 0;
    }
}
book::book(const book& c)
{
    arraylength = c.arraylength;
    listsize = c.listsize;
    a = new address[arraylength];
    for (int i = 0; i < arraylength; i++)
    {
        a[i].name = c.a[i].name;
        a[i].classroom = c.a[i].classroom; 
        a[i].dormitory = c.a[i].dormitory;
        a[i].phone_number = c.a[i].phone_number;
    }
}
void book::insert(book &b)
{
    if (b.listsize == b.arraylength)
    {
        delete []b.a;
        b.a = new address[2*arraylength];
        for (int i = b.arraylength; i < 2*b.arraylength; i++)
        {
            b.a[i].classroom = 0; b.a[i].dormitory = 0; b.a[i].phone_number = 0;
        }
        b.arraylength = b.arraylength * 2;
    }
        cin >> b.a[listsize].name >> b.a[listsize].phone_number >> b.a[listsize].classroom >> b.a[listsize].dormitory;
        listsize++;
}
void book::_delete(book &b,string c)
{
    for (int i = 0; i < listsize; i++)
    {
        if (b.a[i].name == c)
        {
            for (i=i; i < b.listsize; i++)
            {
                b.a[i].classroom = b.a[i+1].classroom;
                b.a[i].dormitory = b.a[i+1].dormitory;
                b.a[i].phone_number = b.a[i+1].phone_number;
                b.a[i].name = b.a[i+1].name;
            }
            a[listsize].classroom = 0; a[listsize].dormitory = 0; a[listsize].phone_number = 0;
            break;
        }
    }
}
void book::compile(book& b,string c)
{
    int n;
    for (int i = 0; i < b.listsize; i++)
    {
        if (b.a[i].name == c)
        {
            cin >> n;
            if (n == 1)
            {
                long long n1;
                cin >> n1;
                b.a[i].phone_number = n1;
            }
            else if (n == 2)
            {
                int n2;
                cin >> n2;
                b.a[i].classroom = n2;
            }
            else if (n == 3)
            {
                int n3;
                cin >> n3;
                b.a[i].dormitory = n3;
            }
        }
    }
}
bool book::find(const book& b,string c)
{
    int i;
    for (i = 0; i < b.listsize; i++)
    {
        if (b.a[i].name == c)
            return true;
    }
    return false;
}
void book::print(const book& b,int n)
{
    long long  sum = 0;
    for (int i = 0; i < b.listsize&&b.a[i].classroom == n; i++)
        sum = sum ^ b.a[i].dormitory;
    cout << sum <<endl;
}
book::~book()
{
    for (int i = 0; i < arraylength; i++)
    {
        delete []a;
    }
}
int main()
{
    int k=0,nn1;
    int nn2;
    cin >> nn1;
    book b;string c;
    for(int i = 0;i<nn1;i++)
    {
        cin>>nn2;
        if (nn2 == 0)
            b.insert(b);
        else if (nn2 == 1)
        {
            cin >> c;
            b._delete(b, c);
        }
        else if (nn2 == 2)
        {
            cin >> c;
            b.compile(b, c);
        }
        else if (nn2 == 3)
        {
            cout << b.find(b, c) << endl;
        }
        else if (nn2 == 4)
        {
            int nnn; cin >> nnn;
            b.print(b,nnn);
        }
    }
    return 0;
}

麻烦大佬我到底是哪里的错误，谢谢！

Answer 1

析构函数有问题

book::~book()
{
    for (int i = 0; i < arraylength; i++)
    {
        delete []a;
    }
}

不能循环执行，执行完第一次，a的地址已经无效了。

改成

book::~book()
{
   delete []a;
}

Answer 2

1. 内存初始化使用 memset 如: memset(ptr, 0, sizeof(struct address) * arraylength)
2. 使用 memcpy 代替成员赋值
3. insert (b.listsize == b.arraylength) 不应该开辟新内存，迁移数据吗？为什么要丢弃原有数据
4. 而且 cin 下一行 listsize++ 不应该是 b.listsize++ 吗
5. 为什么这么写？我看到了 c 的痕迹。你完全可以将数据和函数分开，用两个class1而不是在同一个类中。并且函数应该是 static 的。

b.insert(b) 自己插入自己，做甚？按照你的逻辑不应该是 b.insert(b, value) 吗

---

完完全全可以按照 c 风格写，而不是为了使用 c++ 而强行使用 c++ 特性