Self-made hash tables are not working as expected

I intend to create a hash table of arrays with concatenated lists as elements.The purpose this time is to create a function that adds data to the hash table with addItem and returns the contents of the hash table with displayTable.If you run this program, you will not get a zero and the program will stop.After many attempts, I think the problem is probably while loop or Link*temp=array[i]->getHead() in the displayTable method.Thank you for your understanding.

HashList.h

#include<iostream>
# include <sstream>

using std::string;

class Link
{
private:
    US>string value;
    Link*next;
public:
    Link(string value, Link*next=nullptr) {this->value=value;next=nullptr;}
    ~Link(){}
    US>string getValue() {return value;}
    Link*getNext() {return next;}
    void setNext(Link*next) {this->next=next;}
};

class list
{
private:
    Link*head;
public:
    List() {head=nullptr;}
    void addHead(string value)
    {
        Link*temp = new Link (value, head);
        temp->getNext();
        head = temp;
    }
    Link*getHead() {returnhead;}

};


class HashList {
private:
    intarraySize;
    List**array;
public:
    HashList(){
        arraySize = 7;
        array=newList*[arraySize];
        for (inti=0; i<arraySize;i++)
        {
            array[i] = new List;
        }
    }

    HashList (int size)
    {
        if (size <7)
        {
            size = 7;
        }
        arraySize = size;

        array=newList*[arraySize];
        for (inti=0; i<arraySize;i++)
        {
            array[i] = new List;
        }
    }

    int hash (string value)
    {
        int hashValue = 0;

        // figure out the index
        for (inti=0; i<value.length(); i++)
        {
            hashValue*=128;
            hashValue+=value[i];
            hashValue% = arraySize;
        }

        // return the index
        return hashValue;
    }


    void addItem(string value)
    {
        array [hash(value)] - > addHead(value);
    }

    US>string displayTable()
    {
        std::stringstreams;
        string output;

        for (inti=0; i<arraySize;i++)
        {
            Link*temp=array[i]->getHead();

            if(temp==nullptr)
            {
                ss<<"_empty_";
            }

            while(temp!=nullptr)
            {
                ss<<temp->getValue()<
                temp=temp->getNext();
            }

            ss<<"\n";

        }

        output =ss.str();

        return output;
    }

};

main.cpp

#include<iostream>
# include "HashList.h"

using namespace std;

int main() {
    HashList test;

    test.addItem("Hello");
　　test.addItem("Hello");
    cout<<test.displayTable()<endl;


    return 0;
}

c++

2022-09-29 22:55

1 Answers

Link(string value, Link*next=nullptr) {this->value=value;next=nullptr;}

The next=nullptr here is meaningless.You wanted to do this :

Link(string value, Link*next=nullptr) {this->value=value;this->next=next;}

2022-09-29 22:55

If you have any answers or tips

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