Hash funciton

[MrRobot]

I wrote this code to for HW. I'm supposed to do a hash function and display information about the searched ship, first I have to get the data from a file and then manage it. Although the code has no build errors once I start debugging it suddenly crashes at line #28, which is in the constructor, when the 1st and only object in main is created. I get a message that says "Cannot open file: ../../../../../src/gcc-5.1.0/libgcc/unwind-sjlj.c" I can't start debugging so most likely functions do not do what they are intended to do, but the problem here is the file that cant be open for some reason. I have run this code in other machines with the exact same issue. I have never seen this "error" before and google either apparently :c. HELP.

shiprecords.txt file:
1009 1 "Royal Queen" 2015 160
1010 2 "Carnival" 2016 1600
1019 1 "Ocean King" 2013 110
1029 2 "Royal Prince" 2012 2000
1039 2 "Royal Princess" 2010 2100
1014 2 "Royal Caribbean" 2016 1600

#include <iostream>
#include <fstream>
#include <string>


using namespace std;

struct ships
{
    int serialNum = NULL;
    string type = NULL; /// cargo or pasingers.
    string name = NULL;
    string year = NULL;
    string cap = NULL; ///capacity.
    ships *next = NULL;
};

class LinkedList
{
private:
    ships *List[10];
    ships *head;
public:
    LinkedList()
    {
        string line;
        ifstream file;
        ships *newNode = new ships;
        ships *p;

        file.open("shiprecords.txt");
        if(file.is_open())
        {
            while(!file.eof()) 
            {
                getline(file, line); /// reads a line from file until end of file.
                for(int k = 0; line.length() >= 3; k++)  ///takes the line and breaks it into variables.
                {
                    char y = NULL;
                    if(line[0] == ' ')
                    {
                        int j;
                        for(j = 1; j < line.length(); j++)
                        if(line[j] != ' ')
                            break;
                        line.erase(0, j);
                    }
                    if(line[0] == '"')
                    {
                        y = '"';
                        line.erase(0, 1);
                    }
                    else
                        y = ' ';
                    int i;
                    for (i = 0; i < line.length(); i++)
                        if (line[i] == y)
                            break;
                    switch(k) ///assigns the selected text from the line and assigns it to a variable.
                    {
                        case 0: newNode->serialNum = stoi(line.substr(0, i));
                                break;
                        case 1: newNode->type = line.substr(0, i);
                                break;
                        case 2: newNode->name = line.substr(0, i);
                                break;
                        case 3: newNode->year = line.substr(0, i);
                                break;
                        case 4: newNode->cap = line.substr(0, i);
                                break;
                    }
                    line = line.erase(0, i + 1);
                }
                if(head != NULL) ///Once the object has all values assigned it links them together to create a list.
                {
                    while(p->next != NULL)
                        p = p->next;
                    p->next =newNode;
                }
                else
                    head = newNode;
            }
        }
        else
            cout << "File not found.";
    }



    void Hash() ///takes object from list and assigns them to their respective index in the List[] array
    {
        ships *n = head;
        while( n->next != NULL)
        {
            if(List[n->serialNum % 10] == NULL)
            {
                List[n->serialNum % 10] = new ships;
                List[n->serialNum % 10] = n;
            }
            else
            {
                ships *prevNode = NULL;
                ships *p = List[n->serialNum % 10];
                while(p->next != NULL && p->serialNum < n->serialNum)
                {
                    prevNode = p;
                    p = p->next;
                }
                if(p == List[n->serialNum % 10] && p->serialNum > n->serialNum)
                {
                    n->next = p;
                    List[n->serialNum % 10] = n;
                }
                else if(!p->next && p->serialNum < n->serialNum)
                    p->next = n;
                else
                {
                    prevNode->next = n;
                    n->next = p;
                }
            }
        }
    }

    void DisplayOne(int val)
    {
        ships *p = List[val % 10];
        while(p->next != NULL && p->serialNum != val)
            p = p->next;
        if(p->serialNum == val)
        {
            cout << "Serial Number: " << p->serialNum << endl;
            cout << "Type: " << p->type <<  endl;
            cout << "Name: " << p->name <<  endl;
            cout << "Year Built: " << p->year <<  endl;
            cout << "Capacity: " << p->cap <<  endl;
        }
        else
            cout << "Ship not found." << endl;

    }
    ~LinkedList()
    {
           ///delete dynamic memory.
    }

};

int main()
{
    int value = 1009;
    string line;
    ifstream inp;

        LinkedList record;
        while(!inp.eof())
            record.Hash();
        record.DisplayOne(value);
}

[Peter87]

This is not correct. std::string cannot be null.

    string type = NULL;
    string name = NULL;
    string year = NULL;
    string cap = NULL;

If you want the strings to be empty you don't need to do anything. It's the default.

    string type;
    string name;
    string year;
    string cap;

If you want to be explicit you can do

    string type = {};
    string name = {};
    string year = {};
    string cap = {};

but this is not necessary.

This is also not correct, but harmless. If it didn't work it would just have given you a compilation error.

int serialNum = NULL;

Remember that NULL is for pointers, and pointer-like objects. Also note that in modern C++ we often use nullptr instead of NULL because it has a few advantages.

[tpb]

Also note that in modern C++ we often use nullptr instead of NULL

Even in older C++ we usually used 0. I guess the old (void*)0 definition would cause problems! And if NULL is always defined as plain old 0 (as it should be in C++), then it really has no purpose.
But I guess nullptr is better.

[Peter87]

NULL is always defined as plain old 0 (as it should be in C++)

NULL is allowed to be defined as nullptr since C++11 but I'm not sure if any implementation actually do so.

[tpb]

NULL is allowed to be defined as nullptr since C++11

That's interesting. This is how it looks in gcc:

/* A null pointer constant.  */
#if defined (_STDDEF_H) || defined (__need_NULL)
#undef NULL		/* in case <stdio.h> has defined it. */
#ifdef __GNUG__
#define NULL __null
#else   /* G++ */
#ifndef __cplusplus
#define NULL ((void *)0)
#else   /* C++ */
#define NULL 0
#endif  /* C++ */
#endif  /* G++ */
#endif	/* NULL not defined and <stddef.h> or need NULL.  */
#undef	__need_NULL 

[MrRobot]

Thanks, guys, not only for telling me what was the issue but also for explaining.