Linked-list program crashing after adding elements

Question

My program crashes after sequence of inserting head, then inserting tail, every other cases it seems to work. I cant figure it out.

struct Node {
    int key;
    Node *next;
};

struct List {
    Node *head, *tail;
};

void init(List& l) {
    l.head = l.tail = NULL;
}

void insertHead(List& l, int x) {
    Node *temp=new Node;
    temp->next=NULL;
    temp->key=x;
    temp->next=l.head;
    l.head=temp;
}

void insertTail(List& l, int x) {
    Node *temp=new Node;
    temp->key=x;
    temp->next=NULL;
    if(l.head==NULL) {
        l.head = temp;
        l.tail = temp;
    } else {
        l.tail->next=temp;
        l.tail=temp;
    }
}

Thats only part of my code, but I think it will be enough, otherwise here is remaining part http://pastebin.com/WxmYJ0uE

It seems that the error is in the remaining part, had a quick look through it and didn't spot it yet. But you have a lot of noise in your code, like the line temp->next=NULL; in the insertHead above, try cleaning up your code, and it will be a lot easier for you or any other person to fix your code. — Klaus
– Klaus, Commented Mar 15, 2017 at 12:50
Make a test with an empty list, insertHead, then insertTail. Run it in your debugger. — Kenny Ostrom
– Kenny Ostrom, Commented Mar 15, 2017 at 12:56

A.S.H · Accepted Answer · 2017-03-15 13:01:36Z

2

You forgot to set the tail when the first element in the list in inserted.

void insertHead(List& l, int x) {
    Node *temp=new Node;
    temp->next=NULL;
    temp->key=x;
    temp->next=l.head;
    l.head=temp;

    if(l.tail == NULL) l.tail = l.head; // <-- you forgot this
}

answered Mar 15, 2017 at 13:01

A.S.H

29.4k6 gold badges25 silver badges50 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Linked-list program crashing after adding elements

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related