How do I add data to the append instead of the back in Linked List code?

Below is part of the singly linked list code. If you type 'I 1', 'I 2', and 'I 3' after you run it, I want to make sure that the 3 entered later comes out first as the head, but on the other hand, it comes out in the order of 1, 2, and the getHead head comes out as 1. I thought about reversing the order when it was printed, but I don't think this method I thought would work because the first value of the head is still the head when I print out the head. Is there a lot of things that need to be fixed to change it as you want? I don't know because I'm a beginner, and I want to follow the school curriculum, but it's difficultcrying I would appreciate it more if you could explain it easily.

class InputData
{
public:
    int data;
    char query;
};

class Node
{
public:
    Node* next;
    int value;

public:
    Node(InputData* inputData) {
        this->value = inputData->data;
    }

    Node(int value) {
        next = NULL;
        this->value = value;
    }

    Node() {
        next = NULL;
        this->value = -1;
    }

    void print() {
        cout << value << endl;
    }
};


InputData* getInputData(string input) {
    InputData* inputData = new InputData();

    std::string delim = " ";
    std::string token;
    int pos = input.find(delim);
    if (pos != std::string::npos) {
        token = input.substr(0, pos);
        inputData->query = token[0];
        input.erase(0, pos + delim.length());
    } } else if (input.length() > 0) {
        inputData->query = input[0];
    }

    if (input.length() > 0) {
        inputData->data = atoi(input.c_str());
    }

    return inputData;
}

void insertData(Node** root, InputData* inputData) {
    if (*root == NULL) {
        *root = new Node(inputData);
        return;
    }
    Node* nextNode = *root;
    while (nextNode->next != NULL) {
        nextNode = nextNode->next;
    }
    nextNode->next = new Node(inputData);

Node* getHeadNode(Node* root) {
    if (root != NULL) {
        return root;
    }
    return NULL;
}

void printNode(Node* root) {
    Node* nextNode = root;
    while (true) {
        if (nextNode != NULL) {
            printf("%d ", nextNode->value);
            nextNode = nextNode->next;
        }
        else {
            break;
        }
    }
}
}

c++

2022-09-22 10:34

1 Answers

I think you can use it more easily if it's a double connection, but I can't help it if it's a single.

void AppendData (Node** root, Node** pos/*current location*/, InputData* inputData)
 {
    if (*root == NULL) {
        *root = new Node(inputData);
        *pos = *root;
        return;
    }

    if(*pos == NULL)
    {
        // You can have them put before or behind the root when they don't know where they are.
        return;
    }

    If ( *root!= *pos) // inserted in the middle, not root
    {
        Node* nextNode = *root;

        while (nextNode->next != *pos) {
            nextNode = nextNode->next;
        }

        nextNode->next = new Node(inputData);
        (nextNode->next)->next = *pos;
    }
    else // if inserted before root (root == pos)
    {
        *root = new Node(inputData);
        (*root)->next = *pos;
    }
 }

Inserting the front is relatively easy. If you connect to the next of the pre-created object, you insert it backwards, but if you connect to the next of the object you created later, the pre-created object is pushed back.

Therefore, the value entered first goes back, and the value entered later goes forward.

2022-09-22 10:34

If you have any answers or tips

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